Heavies refer to the larger standard breeds, they are usually dual purpose. Birds bred for meat usually grow really fast, these guys should get pretty big though.
Many breeds share the same coloring when they grow up even though they are different breeds. Usually wherever you bought them should have a list of the possibilities they sold you.
The brown striped ones might be Partridge plumage, or dark brown. The yellow chicks will be white, mostly white or buff. The orange-ish red ones should be a red variety such as Rhode island or New Hampshire reds. Black mixed with yellow chicks will be black, mostly black or silver laced.
On the Murray Mcmurray hatchery website they have short chick videos for most of the breeds they have. If any have feathers on their legs you might have a Brahma. Most of the heavy assortments I've seen for sale don't generally include rare breeds. Although some places throw in an unknown freebee in the mix.