For the most part it's generally straight forward, but here's a a bit of clarification in case it helps:
- Overall ranking is determined by overall point value. (Top point ranking on profile)
- Battle points is the aggregate value of your offensive & defensive battle points. (Middle point ranking on profile)
- Grepolis-score is based off of cumulative achievements from server to server. (Bottom point ranking on profile)
- Attackers is based off of attacking battle points earned.
- Defenders is based off of defensive battle points earned.
Generally, 1 BP is earned per 1 population killed (excluding 2x BP buffs, and ally BP de-buff)