I'd suggest trying to find the website of a company called Groove Tubes,there are brief explanations of what to expect of each type of tube,both the ones you mentioned and others.Cheers!
unless you're running a Rectifier or other amp with switchable bias, you may want to have a tech check your bias and make sure it's correct for your amp. The correct tube for the bias setting will sound better in either case (and it is possible to re-set your bias for different tubes).