Is there a real difference between the red gears and sprockets vs the green ones? Is it just one is older than the other?
There’s no difference.
The main difference, is that some of the newer high strength red gears will have a built-in metal insert for HS axles, whereas the older green ones won’t.
Essentially, if the gear is red, and has a metal HS insert built in, it will be stronger.
it depends on which one it is, but there are better holes on the red ones for alignment
I think the red gears are stronger and easier to work with.