point-free style and partially applied functions

Question

In Haskell there are two concepts that doesn't look like they are the same, but I don't understand the difference. They are "point-free style" and "partially applied functions".

For point-free styles I'm going to get this example:

instead of: sum xs = foldr (+) 0 xs
we can use: sum = foldr (+) 0

Because xs is on both sides we can omit it.

And for partially applied functions, I'm going to get this example:

increment = add 1   

which could be increment n = add 1 n , because at the moment of calling it, you need to do it with the argument, just as the first example.

So, what's the real difference between them?

But, for me, in the end it's the same.

Answer 1

Pointfree style - a style of function implementation

Partially applied function - it is a technique of creating new functions

Point-free uses partially applied functions but there are other techniques and combinators https://wiki.haskell.org/Pointfree

Another common Pointfree technique is function composition

plus2 = increment . increment