Are there different forms of restless leg syndrome?

Not really. Restless leg syndrome, refers to a condition in which there is this feeling that you must move your legs. Traditionally, involuntary movements of the legs is not restless leg syndrome. However, there has been a trend by some authors to refer to restless leg syndrome as both.
Yes. In that there are different causes, and not everything that makes your legs move all the time (which is akasthesia) is really restless leg syndrome. Rls is mostly nocturnal, and interferes with normal sleep patterns, causing daytime somnolence and possibly worse problems. It can be caused by several medications and iron deficiency. The diagnosis should be made by formal sleep study.