The difference is that it's not dealt with entirely in the compile phase. i.e. language features that are checked at compilation and known to be true that are n

The difference is that it's not dealt with entirely in the compile phase. i.e. language features that are checked at compilation and known to be true that are not needed at runtime. The Haskell `newtype` example I gave was meant to illustrate this, as newtype's are respected by the type system and then are treated as the underlying type at runtime.