Programming style question

[Adrian Hey]

Hello,

Here's something I've always wanted to know but
have never dared ask until now (it seems so basic).

If I have defined a function like this..
	f <args> = <blah> <args>
it could be re-written..
	f = <blah>

I had always assumed the internal representation of
these 2 definitions would be identical (and should
yield identical code), but it appears that isn't so
(with ghc at least). So..

 Is there a semantic difference between the two? 
 Which form is likely to result in faster code?

Thanks
--
Adrian Hey