Is there a difference between Euler systems and Kolyvagin systems - or do they refer to the same thing? For example there is the Heegner point Euler system, but you don't really see a Heegner point Kolyvagin system.

Also, Rubin-Mazur prove that the space of Kolyvagin system is free of rank one (under certain conditions) - is something similar true for Euler systems?