I'm not sure that it's possible from photos. This web site gives some information about identification and says there are 10,000 species! It might help somewhat to know in what part of the world the ones in question are located.
https://www.fieldmuseum.org/fi...
I think I would assume they are doing the usual millipede thing and living primarily on decaying material unless there's some evidence to the contrary. They can sometimes be plant pests.
