The dev team for Steem mostly builds the Steem blockchain. They also run Steemit but the blockchain is their focus. Every action you take here - posting, commenting, voting, managing SP - is a blockchain action. Steemit the website is just a way to display them.
There are other people who have built other ways to display the same blockchain, and SteemPeak is one of those. (So are busy.io, d.tube, and a bunch of others.) They're basically all skins for the same system.
RE: A Bit Curious Contest #2 100 SBD in Prizes - 7-10-18