Hook call vs hook function

[IzNoGoD]

iirc one of them is reversible while the other is not. I've used the hooked stuff from time to time to hijack a function without impairing its normal operation, but adding a single instruction (or function call) to it.

[thawalrus]

Yes, the call hook can easily be repaired by putting the original function address there again. For the other one you need to repair the function itself or creating a 'trampoline' to have the original function procedure executed.