Congratulations on getting some fish out in the Big Lake. Good Work!! Gotta love trout on the bbq. MMMM MMMMM Good!!
Crazy to see the difference in shape in them. The short guy certainly had a brown trout shape, but from the picture it does look like a rainbow by the colours, although it isn't real clear. Are you sure it was a rainbow? I think there are variations in size and shape just like in humans. Is a wierd looking Rainbow though.
As for the Rainbow vs. Steelhead. There is essentially no physical difference (sometimes a little colour variation) between a Rainbow and a Steelhead. They are the same species. A Steelhead is a rainbow trout that migrates out of a stream and into a big lake or ocean for 2 or 3 years until it matures and then returns to a stream to spawn. A rainbow trout "land locked" and does not migrate out to a big body of water to mature.
Any Rainbow caught in Lake Ontario is a steelhead, but its still a rainbow.
Scott