Hey guys. I'll try to help.

• Steem Power is just steem locked up in a way to affect your voting power / payouts. The more you have in SP (steem power), the more you get from upvotes and also the more your are able to give out VIA an upvote. It is your POWER on the site. If you put Steem into SP, it takes 13 weeks of equal payments to exit SP back into regular Steem that you can sell on an exchange. Most people put everything into SP if they are long on the platform (like me).
• SBD are "Steem backed dollars" used to help assist with the economics of steem, it creates liquidity and also helps stabilize Steem value. People on here use SBD to pay for services like Hive account@randowhale and to tip people above and beyond an upvote for great content or great service to the Steem community.
• Steem is just steem. If you have STEEM, you have the actual blockchain asset this entire network is based upon. It's like owning a share in Steem's future.

Any questions, hit me up and I'll try to clarify!