[Haskell-beginners] $ versus .

I've got this

init $ tail [1,2,3] [2]

and this

chopEnds = init $ tail chopEnds [1,2,3] [1,2]

What happened? Why is it not just init $ tail [1,2,3] ? This works fine

chopEnds2 = init . tail chopEnds2 [1,2,3] [2]

What am I missing? LB