Nolvasan is Chlorhexidine diacetate - a strong disinfectant registered with the Environmental Protection Agency.
Hibiclens is Chlorhexidine Gluconate - also known as surgical scrub! A strong disinfectand used by some hospitals as a surgical scrub to prevent cross-contamination and ect.
There is a difference between these two products - but nothing that you or I need to worry about. Both of these disinfectants are strong enough to wipe out the 'bugs' that snake keepers run into. Make sure the chlorhexidine you are looking at is close to 4% and you are good to go!
(by the way, I am at work at the Pharmacy, and just checked all my factoids with my Pharmacist)