Sims 3 & Sims 4 are like apples & oranges.
With Sims 3, you get open worlds, color wheel/textures plus Fairies/Genies/Werewolves, Lunar Moon & so forth.
With Sims 4, you can actually build like crazy, Gallery, better Aliens/Mermaids/Witches/Vampires, way more worlds, way more cheat codes & can muliplate the environment & weather of you worlds.
Plus, you can make your own Hybrids with the occults.
As for multiplay, it's not that hard to go from one household to play with & the other, just select manage world & you're back on the map to select another household or even another world.
You can even have multiple Game Saves. I have 6 on the go for my different timelines.
Basically, Sims 4 has alot of potential & with the new devs they are finally letting the game grow regardless of what's still missing. We will probably eventually see that.
You are smart for waiting this long to begin your Sims 4 experience. My daughter & I made the mistake of starting in year one back in 2014 when it was an empty game. Our reasons was because Sims 3 kept freezing up every 30 seconds & couldn't hold the 20 packs. :s Sims 4 has over 40 packs & still holding. :p However, my advice is don't ever get any mods or mccs, just play vanilla & remember to clean out your cache & tray files & select repairs after patches or packs. And have fun. :p
