@SianAF148 There are lots of comparison sites, but they're not necessarily completely accurate, and conversely, some give way too much information to be useful. This is also complicated by the fact that a given laptop's design and manufacturer settings can have a significant impact on performance for various reasons. This is more complicated than I want to get into, but in general terms, the manufacturer tunes power draw and clock speed targets to match temperature and other targets. You wouldn't see a major loss in performance, at least in your price range, but minor ones definitely happen.
But in general, yes, higher numbers are better. Both Nvidia and AMD use the first digit to designate the generation, with each generation being somewhat faster than the previous one. AMD's second digit and Nvidia's third designate the rank within the generation. As I mentioned, the 3050 is maybe 30% faster than the 1650 in gaming, but the 1660 ti is faster than the 3050 even though it's older.
The AMD RX 6500M might be 10% slower than an Nvidia RTX 3050 and 20% faster than a GTX 1650. But there's a lot of variation from one game to the next, much more when comparing AMD to Nvidia than when staying with one brand. I don't have data for Sims 4 itself, but I'd still go with a 6500M over a 1650: I haven't seen any evidence of the game running unusually slowly on AMD cards, and the GPU really is faster.
In your price range, you're not really going to see other options for a dedicated graphics card. A 6600M would be significantly faster than a 3050 and basically on par with a 3060, but laptops with those mostly cost £900 and up.
For integrated graphics chips, the key is the processor, with each CPU having a specific iGPU built into it. Here again, AMD uses the first number to designate the generation and the second to designate rank, e.g. the 5500U is the newer version of the 4500U, and the 5700U is faster than the 5500U. But not all improvements are meaningful: the 5500U and 5625U have the same graphics chip, and both processors are more than fast enough for Sims 4, so there's no effective difference between them as far as the game is concerned.
The 1650 is still twice as fast as the graphics chip in the 5700U, so you're really looking at two completely different categories of laptop.