I am not sure if the green scapular is substantially different from the brown, but a brown scapular is technically made from plain brown cloth and has no images whatsoever. As long as a green scapular is green in color, it should be fine.
The green scapular is different and a bit unique when compared to others (brown, red, black, etc.). You can think of it more like a rosary in that you can continue to use it after it’s been blessed until it’s simply no longer functional (falling apart beyond repair). You aren’t “invested” in it; it’s simply blessed. If you get another, have it blessed as well — unlike the others, the blessing doesn’t “transfer” to new ones.
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