How different between B&W 804s & B&W 805s????

I know that floorstanding speakers always better than the bookshelf...

I don't know what has made you think this but that is not necessarily true.

What you can expect is a fuller sound with the 804S as they have more bottom end to them.

Which to upgrade first, speakers or amp, would be your call; what is your current amp?

thanks for your response. Yes i want fuller sound and more bass .That's what i mean better :-)I'm using Marantz Pm14MK2.

"I know that floorstanding speakers always better than the bookshelf..."

Second Brianmgrarcom, Not necesarily true. Mate your 805s to a high quality subwoofer that integrates seamless (e.g. Rel) and you'll get dynamics at least as good as the 804's if not better, and even a fuller sound than the provided by these floorstanders.
Jov