From what I remember from the show, Reach Scarabs in Young Justice are primarily nanotech run by an A.I. and are artificial beings built by the Reach in an attempt to counter Green Lanterns. While highly advanced, they are also far less versatile in the variety of constructs they can make or the size of said constructs. They are really just a poor mans power ring, with their primary advantages being that they don't have to recharge from a separate power source, the armor and weapons are not dependent on the mental state of the user, they can be remote operated by Reach officials and they are dedicated weapons and infiltration tools compared to Green Lantern police officers(ones that cant use their power rings to kill at that). Definitely better then any natively developed power armor on earth though.