Yes, I think they're blue Swedishes because of their blue-gray color and it looks like they have yellowish chests. Perhaps you can show us a front photo of them. Swedish ducks will have a distinct yellow patch in the front, Campbells don't. However, they can be a mix between Swedish and Campbells which seems to be very common.
Rouens generally look like mallards and usually have two eye stripes near their eye, but sometimes the second stripe is not very visible. Rouens are large versions of mallards and don't fly. They're usually used for meat and eggs and have a pekin-like personality, but the beautiful mallard coloring. Rouens will grow quicker than mallards.