Exercise for the reader: determine whether these sets are different in a meaningful way.
Actually, its neither, if you really think about it. Currency users (in exchange) are more important than either miners or holders (with the caveat that you need some number > 0 of miners to validate exchanges) to whether a protocol change has economic effect, but once some group adopts a protocol change, what you have is a fork into two separate currencies until a consensus is achieved.
Passive currency holders have little driving force in this; currency users are the main driving force, because wherever its being used is where it will have value. Miners have some force because without some of them, the system collapses.
And among currency users, the ones that matter the most are the ones that accept bitcoin for goods and services, not the ones that spend it. (In the "steady state" those should be approximately the same, but as long as mining is still producing coins you can have miners/spenders that aren't accepters, and even in the steady state you could have people who inherit hoards and slowly deplete them as users that aren't accepting.)