Comment by Akronymus

In f#'s case, there is the trifecta of everything being an expression, static typing and default immutability. This means you often write code like this:

let foo = if bar then baz else someDefault

Due to it being an expression you assign what the if evaluates to to foo. Due to static typing, the compiler checks that both branches return the same type. Due to the default immutability you don't declare and assign in separate steps. What this results in, is that accidentally using the wrong indentation for something usually results in an error at compile time, at the latest.

Compared to how python does significant whitespace is that it's dynamic typing + statement based, which means you can easily end up assigning different types to the same variable in different branches of an if, for example.

I hope I explained it in understandable terms