CBMP is a foot position. Howard: "The placing of the stepping foot, forward or back, onto or across the line of the other foot, giving the appearance of CBM having been used, but without turning the body".
The last bit is quite important, but it is not uncommon to find steps where CBM & CBMP are actually used together, but that is the exception, and not the rule. CBM (Contrary Body Movement) is a body action (not a foot position) "used to initiate turn. It is the moving of the opposite side of the body towards the stepping foot, either forward or backward" (Howard).
Beware of anyone who tells you that their answer is all you need to know. That's not for them to say, and it is counter to the spirit of a discussion forum; where a range of opinions is to be expected, but where factually correct answers to a direct question are always welcome.