Not equivalent. Adjacent?So a service top would be the top equivalent of power bottom?
IMO A power bottom is in it for themselves and would take on all cocks available to satiate the unquenchable ass hunger. I don't believe a PB cares who fucks them once they start getting into the groove.
A service top provides topping to one(or more) persons on request.
A Bull might be the equivalent of the Power Bottom. They exist and need to fuck throats, holes, a bent leg, an arm pit, that's what they do. Like a PB needing poles, a Bull needs holes. I don't think a Bull cares who they fuck when the party's rockin.
Once you get into specifics of what is what and who's supposed to do or be what, it gets very complicated on paper. The easiest and sadly rarest way to figure out what works for you is to talk to a person in the lifestyle face to face. Don't be shy and do ask a million questions. People with lifestyle kinks are generally open to honest discussion about it.
One of the best introductory ways to get involved with any aspect of the lifestyle is a BDSM Munch(not what it sounds like).
A Munch is a public get together, usually over coffee and snacks and held in safe or accepting public places. Sex or overt acts is almost always frowned upon and the offender would probably be asked to leave.
You get to meet people into different lifestyles and talk about anything kink related or informational. You get to network and maybe make new friends. None of which is discouraged and if you and a person happen to duck out of the meeting and head away from the Munch to play, no one cares. Kinda like cruising, don't be overt and drooly. You get bant pretty quick and no one goes to a munch to hook up normally.
The point of Munches are networking and community.
This is extremely important in BDSM lifestyles because there are so many vulnerable people involved. A good community can help each other much like a support group where as no community leaves people in shitty situations, alone. There is a remarkable number of bad/inexperienced Doms and horrific Masters and conversely, there are people willing to subject themselves to atrocities because they don't know any better and think that's what the life is all about.
There is a happy medium mixed into BDSM, it's all A la carte and nothing says you have to live it 24/7. Learn a ton, ask more questions and talk to people who share an interest.
Also, pretty stoned and feel weird. Probably won't remember writing this. Thinking of the fun bits of the life got my dick hard. Thank you for unintentionally bringing back the memories.