Yep, that sounds like a Rock...they look like Rocks as well...but check...they should have a red earlobe if White Rock.
If they have a white earlobe, then they may be White Leghorn.
They aren't Cornish Cross as they have fine legs and aren't growing quickly (and wrong body type too).
LofMc
Dixie Rainbows are a hybrid that has a lot of variety in feather patterns....McMurray's site states "no two birds are alike."
I don't think of pure white when I think of a Dixie Rainbow. Typically I think of a red barred, mottled bird. But I've seen photos of those that are buff.
There is a...