I have been a skilled Coder on Scratch but ever since I moved here, the blocks are the same and the editor is almost the same, but why do my skills feel weak now?
There are a bunch of big ideas in Snap! that aren’t in Scratch. See this for some examples.
Similar to what bh said, 
lets you do more stuff in the style of Scratch.
You know how ST’s rejected Tables (2D lists) in scratch? Well…
Case Sensitivity, temporary variables, custom Reporter blocks, etc.
Try reading the Snap! manual for more information about the key ideas!