A recovery disk usually points to a (hidden) partition on your disk which has all the restore files on it, when you run it, it will restore your pcs hard disk to the exact state it was in when it left the factory. This means all progs, branding, etc that was on the pc when you brought it, including any trial software, will be restored.
A retail brought disk (eg from pc world in a shrink wrapped box) just has the os on it. If you (re)installed the os from this only the operating system would be installed, no branding (ie internet explorer would not be have HP on the title bar), no additional progs that the manufacturer pre-installed (ie no anti-virus, ms works, etc).
Personally, I prefer the retail disk route, this way you only install what you want, no 60 day trial version of sw you don't want anyway.
Hope this helps.