missweetmarie, you may be seeing street style salsa that uses the mambo basic. Remember that most people dancing in the latin clubs have never had a ballroom dance lesson and so do not dance ballroom mambo. Street salsa has nearly an endless number of moves and the styling is more personalized and thus varies greatly from one person to another. Ballroom dance, which is actually expensive to learn, is well-defined and follows much more rigid school figures and styling.
So if it is street salsa you are seeing and liking, just jump right in and find a local independant latin/salsa studio to teach you, rather than a ballroom studio. Thats what I did (actually I take ballroom lessons from FA and street salsa lessons from a local indy). It is wonderful!