Unfortunately, on this level, STEEM is a different beast. I suggest looking up busy.org as I believe they are responsible for the majority of the STEEM architecture. Steemit is just a service on top of it leveraging it I believe. Steem was premined (I think). Meaning that they mined it all prior to launch. Don't ask me how this works as I am still curious myself. Basically mining comes in the form of curating on STEEM. post and like and resteem... Also means transactions aren't really all that secure compares to something like Bitcoin's blockchain. but we could argue and debate this stuff all day...