SBD is supposed to peg to the US dollar. It isn't perfect but it does seem to get around to pegging eventually. After rising to about $10 last year it ended up back at $1. After dropping to 50 cents a month or two ago it has ended up back close to a dollar (94 cents currently, was recently as high as 98 cents).

STEEM is not pegged to anything. It is worth what it is worth like any other crypto (i.e. more when there are a lot of buyers and less when there are a lot of sellers).

You should not expect there to be any particular relationship between SBD and STEEM.