Honey locust has multi-pointed thorns along the trunk. Black locust has singular thorns on the smaller branches. They both have seed pods, honey locust pods can be 12" long and 1" or more wide. Black locust pods are about 4" long and maybe 1/2" wide.
Honey locust isn't the best bow wood but if you overbuild the bow it should make a good bow. It probably reacts well to belly tempering.