Three Steem 'coins'.
SP, just for power on the site, more sp, more value in your vote.
SBD, pegged to USD+/-, gets you one US dollar of Steem, on the internal market. Often sells for more than one USD on the external exchanges.
Steem, full floating crypto coin.
Not all hardforks result in two coins, just obsolete rules.
ESteem is a gui, not a coin, yet.
The blockchain is called Graphene and it is shared architecture with bitshares, but a separate chain.