It feels very similar, gameplay-wise. Traversal is still super engaging and fun, the combat is pretty fluid (it starts out kinda rough until you upgrade your skills), and visually it's amazing. If you liked either of the previous games, you'll like this one. It hits all the same notes, plus some new ones.
As for differences, there aren't many. You can fly/glide now, you can switch between Spider Men, there's some new gadgets, some new skills to compliment the old ones, etc.
There's a lot of low-key flexes the devs snuck in that you might not even notice while you're playing, which just goes to show exactly how well they've optimized the game. Things like full-city zooms with no pop-in, extreme close-ups, etc.