Does it make a big difference? I heard 60hz freesync would make a bigger difference than high refresh, it looked nice when I had 144hz but aside from me sliding my mouse it didn’t really change anything.

60Hz is absolute minimum, but it's also mostly sufficient.

120-144Hz is a lot nicer though. All animations, scrolling, even just moving the pointer, look and feel smoother and snappier.

Depends on the person, but for me it makes a big difference.