A friend and I split an order of 25 RIR chicks last year. I didn't understand the whole production red thing either, at the time. All of ours have been very productive layers, though a few actually laid the big brown eggs they're supposed to.
As for the difference? If there not listed as Heritage RIR, or from a reputable breeder, odds are they are production reds. Don't know for sure, but the rumor mill suggests they were crossed with Leghorns somewhere down the line to beef up egg production. Heritage RIR hens are nowhere near the egg laying machines that production reds are, but if bred properly they will go broody, lay bigger eggs though not as frequently, and will likely be bigger birds. If you have any roos, they will likely have more brown than that deep mahogany red of the Heritage RIR. For fun, I think I have a few of mine stored on here...
This is probably a month before laying.
This about the time they started laying.
That roo has the body type of the heritage, but the shiny plumage should be redder and cover the whole body. A few of the hens had decent color, but most were just brown and a couple were more goldish.
After seeing all the other pics, I guess its a trademark of production reds to have those floppy combs.
