No toddlers or pools in sims 4
You can select walking styles and create a sim is more advanced,
The sims moods effect them more
New opportunities
Build mode more advanced
The create a sim is a lot more specific, allowing you to put better detail into how your sims look
The sims walk differently depending on how they're feeling
There actions are determined by how they're feeling
Making houses is supposed to be a lot easier
There's a wider range of furniture and other things to decorate your house
I can't think of anything else lol