Ashley,
I cannot tell you the difference between IBM and SAM but also know that there is an FCM (Fellowship of Christian Magicians). Now, to get into some local magic clubs they may or may not force you to join the "national" organization as well. We have a local magic club and only about half the members are actual IBM members simply because the choose not to pay the dues and don't want the magazine subscription to The Linking Ring. Clubs / Rings are definitely the easiest way to take your magic to the next level and it helps you "network" immensely.