First, their are differences between common BDSM activities. I imagine that once a person decides what kind of activity (-ies) they want to be participates in determines what you are. The following is my understanding from my BDSM readings:

a) TOP/bottom: it is about the physical body.....pleasure/pain. The TOP does things to the bottom, spanking, clothe pins, crop, penetration, etc and the bottom reacts. The TOP then reacts......it is a physical dance. Once play is over the two participants are equal.

b) DOM/submissive is about the mental body.....specifically power. The DOM/DOMME is in complete control during the scene and the submissive submits to whatever the DOM wants. Now there can be sexual subs who only submit in sex and nothing else. The is the Daddy DOM/lil girl where the DOM is a daddy like figure (NOT the father) and the lil girl (NOT a daughter) submits to Daddy DOM. This is NOT incest or anything like that. It is just the relationship. The Daddy DOM pampers and disciplines his lil girl.

c) Master/slave is beyond DOM/sub since it is supposed to be 24/7. It is about spiritual body....submitting to subconcious urges. Many slaves can't remember when they weren't submissive and wanted to submit. The relationship is like above and contracts for periods of time are signed by two equal people. Only after the contract is signed does the roles come into play. As a rule, the slave ASKS the Master to be his or her slave.

d) finally there is Owner/slave.....an extreme Master/slave that is without any limits or whatever is negotiated.