- SBD = STEEM backed Dollar a SBD "should" be ever worth around 1$ the only good use for it I found is to pay for Bots
- STEEM is used to Powerup or to trade in other cryptocurrencies
- SP = STEEMpower = Uppowered or earned STEEM which increase your influence and the worth of your Vote. If you want to Powerdown it takes 3 months change back from STEEMpower to STEEM
For more details look into the FAQ at https://steemit.com/faq.html
Thank you very much my friend, thank you for asking me