There are places in this country of ours where you'll have more than one subspecies of bird, though they are fairly few and far.

Easiest way to go about it is by looking at the color of the tips of the tail feathers. Rios like you are used to seeing are a very buff/light brown color. They look white, until you see one thats really white.... Merriams turkeys have a much much whiter fan tail tip than Rios. Easterns are much darker, often a rich stained oak/cherry dark brown that can fade to almost black. Osceolas are much the same as easterns... way to tell them apart is to look at the wings... or if you shot it south of Orlando... its an osceola (95% sure bet). Goulds are mostly in Mexico, though there are aparently a few in Arizona, though WAY south... they are almost totally black, save those tail tips which are stunningly white. Ocellateds look like a peacock, don't gobble, and are found only on the Yucatan Penn. of Mexico.