Ladies, step aside, let the online warrior through:
PP are your “player Points” and there are universal for your account, regardless of which character you use. I forgot the name of the calculating system it is based on, but it was invented to measure the skill gap of chess players originally.
basically: If you win (lose) against someone who has far more PP than you (far less) the more point you gain (lose), with 128 PP as a maximum. So if you fight someone with exact the same PP you will get/lose 64 PP respectively. Roughly every 32 PP you will get/lose one PP more after the fight, so that the maximum is at ~2000 PP difference.
If you fight with your 200 PP a person with 2200 PP you will get 128 PP for a win and he would get only 1 PP for a win but lose 128 PP .
Everything clear so far?
Good now for BP These are different. they measure the experience with your character, Ranks start with D to D+ to C to C+ and so on up to A+ and further ( Master/Grandmaster)
Until Rank B it is very hard to lose BP, with D and D+ even impossible, no matter how often you lose.
With Rank B upward the normal system comes into play, you can lose points here and even be degraded back to C+.
The system is a little more complicated, you can remember this:
Every 1000 BP difference in the same rank (or two ranks away as a maximum in fact), you gain/lose one additional BP.
The maximum you can gain are 65 BP
The maximum you can lose are 45 BP
If you fight a char with the same BP (within 1000 BP) and the same Rank you get/lose 35 BP. B Rank 7000 BP vs. B Rank 5600BP would only get the 7000 guy 34 Points for a win.
You win more points with a win against a higher ranked character, but interestingly you lose the most points against a character who is slightly lower ranked than you, but not too far away in ranks. If you lose as an A Rank Player against a B rank Player you lose 45 Points but, if you lose against a C+ layer you lose only 20 BP. Both players (B and C+) will get 65 BP for their win though.
In Summary: theoretically you could lose all you PP but never all your BP, but you need a 0-100 loss streak or something for that to happen.