About Types of Mods:XML/tuning mods:
The most common mod that most people will shop around for is the XML/tuning mod. It is the easiest mod to make, and so you will find multiple mods that do essentially the same thing, and change the same bit of XML/tuning code. The chances are good that one modder didn't copy the other modder. There are only a finite number of tweaks that can be done to a particular bit of code, after all.
That being said, you will want to carefully read the modder's explanation of what their particular mod does, because they may have combined two modifications into one mod.
Some websites, like
TFM’s Naughty Sims Asylum do only XML/tuning mods. The modders on that website will try to assure that you know which of their mods will conflict with another modder's mods on that site. But since they are always creating mods, the final responsibility of preventing conflicts will still rest with you.
On other sites, like Simlogical, NRAAS, and Mod The Sims, you will have to either choose the proper category for XML/tuning mods, or read each part of their respective sites to determine which kind of mod it is.
The XML/tuning mods are patch level dependent, and should match your patch level unless the modder specifically says the mod does not need updating. Check both the place it was originally posted, and also any comments made after that for an indication of whether or not the mod is updated to your patch level. Some modders have a stickied post that shows what mods have or have not been fully updated to the latest patch.
If you want to try your hand at learning XML/tuning modding, check out the tutorials at Mod The Sims (NRAAS also has something about this, on their site). You will need to learn the basics about using the S3PE program, which can be found at Simlogical.
Override mods:
Some override mods replace an EA original with a changed version. They do not change the original. They just force the game to read the changed version first, so it gets used instead. The mod may replace lighting/water/terrain in a world. Or it may replace an object, giving you a version of that object with particular changes made (like enabling the object to be recolorable, for instance). A mod may replace a feature, like giving your faeries different shaped wings.
Other override mods change what shows up in CAS, or change whether an action is autonomous or not.
An override mod may even allow you to view startup screens from a previous EP of your choice, even though you have ITF installed.
Generally, you can only use one override mod of a particular type. You can only have one lighting mod at a time, for example.
Object mods:
Object mods are changes to a particular object that may give you a new object with added functions or a new object with some functions removed. The object mod may be written to give you the object in addition to the original EA object, or it may be written to override the original EA object.
One example of an object mod is a piece of art that only showed one version of picture within a certain frame. The object mod unlocks three versions of a picture to be shown in that same frame. Or the original EA version had a stencil, and the object mod gives you both the stencil and stencil free versions in the same object. Or, an original EA object may not allow for recoloring, but the object mod allows you to recolor one or more parts of the object. Or it may even be an object that looks like a hand-held harp, but works like a guitar in the game.
Generally, an object mod will not be patch level dependent. (On rare occasion, this is not true, however. Object mods had to be updated around the time Pets was released. You will need to check old object mods with TSR RigFix, to prevent "blue lot" corruption, which irrevocably destroys a save.)
Object mods that are not also an override will usually not conflict with each other. They are separate objects that will be added to your game. But you will probably want to choose the most useful one, so your game isn't cluttered with similar objects.
Non-core scripting mods:
These mods change or add scripts, rather than just tweaking a tiny bit of code. They require a more in-depth knowledge of coding, and are made by advanced modders. They may add animations, as well.
Scripting mods generally won't conflict with each other. But they will have to match your patch level, unless the modder says they need no change. Check both the initial place the mod was posted and also the comments section, where the modder may have said the mod needed no updating for a certain patch.
Core mods:
Core mods overwrite core code, which is serious code at a very deep level. They are made by very advanced modders, only. Assume core mods will conflict with other core mods unless you have been assured by the modder that their mods will not conflict with another core mod.
Twallen and Pescado are the two most well known and trusted core modders.
It should be noted here that Twallen abandoned his mod before the final two patches of the game. The last version of NRAAS that was written exclusively by Twalllen was made for patch level 1.63 and that patch doesn't have the changes in it required by the game once the servers go down. The last time I looked at NRAAS, they still had links to the last version of the mod that Twallen wrote, exclusively, which is compatible with patch level 1.63 only.
The current version of NRAAS mods has been rewritten to match patch level 1.67, which does contain changes required once the servers go down. Be aware, however, that the NRAAS mod has been changed by a group of talented modders, and is no longer Twallen's mod, in that sense. (Had Twallen been involved, he may or may not have approved those changes. But the group of modders have made every attempt to stay true to Twallen's original vision of his mod, according to their statements on the site.)
Pescado has not changed his awesome mod since May 8, 2014; however, he has yet to say that he has finalized the awesome mod, so you will still be required to download his mod, on a regular schedule, until the awesome mod is finalized. Pescado's mod requires patch 1.67 to run.
The NRAAS mod isn't just a single mod, like awesome mod. Instead, NRAAS is a suite of mods, made to work together.
Initially, the Twallen vision involved making a group of mods that individually modified the game (mixing and matching at will), without resorting to rewriting the core of the game. Eventually, he was forced to also make some core mods, in order to control the game and stop game errors.
NOTE: Twallen's core mods
do conflict with some store PC, and indeed, Twallen was very open that he did not intend to support store PC. So choosing to use Twallen's core mods means being willing to give up whatever store PC items are in conflict. From what I have read about the post-Twallen core mods, this situation has not changed. Do not be surprised if/when you run into problems.
Twallen's original vision means that you will have to learn not just one mod, but many, many mods. Each one has a learning curve. Be prepared to spend a good deal of time acquainting yourself with the ins and outs of the various parts of the NRAAS suite. Read not only the description, but also the comments from other people. Invest your time wisely, and learn what you are getting before you plop it into your game.
Pescado's awesome mod has changed much since the base game. What all it can do now includes so much that he no longer attempts to describe it all on his site. Instead it is all explained in the Read Me document that comes with every version of his mod. READ IT!!
The only way you will learn about awesome mod is to read the Read Me document, because awesome mod works ENTIRELY in the background. You put it on your game, and forget it. In the background, it tirelessly works to fix game errors, optimize play, prevent common problems, remove irritations, etc.
Awesome mod allows for configuration by the player, giving you many choices about how you want your game to play. The first way it does this is with a configuration website page that lets you toggle certain items on or off. The configuration page link is right under the link to download awesome mod, on his site. Once you open the website page, it is titled, in typical Pescado fashion
More Stupid Than You. Read every line and make your choices. Then agree to let the website keep track of your choices, because you need to update the configuration whenever you redownload the awesome mod. And then click the Generate button. The configuration will be saved to your desktop or OS download folder. It is the aweconf.pkg document, and does not need to be uncompressed. Do not try to open it. Put it in the same place you put the awesome mod.
The other way to configure the awesome mod is with the menu accessed through key commands within the game -- the same menu you use for testingcheatsenabled and moveobjects on. When that menu opens, type in the word
help, and you will see a gazillion new options for game manipulation and modification. Well, not really that many, but there are a LOT of them. To really make the most of awesome mod, you will want to be aware of all the new commands he makes available.
One other thing you need to know: Pescado has his own version of the framework that is optimized for his mod. If you got your framework from another source, verify it is also optimized for the awesome mod.
The mod framework package below, that I use in my own game, has been optimized for the awesome mod, but can be used without it, as well. If you are in doubt, then download my version of the framework, to be sure.
http://www.mediafire.com/download/dtidsn2sa4sd10i/Mods.rar 
