They're going after different markets with similar tech (mostly not working, to be honest) or trying different tech. Themis and Prometheus are entirely unoriginal designs. (Which is fine. Their point isn't to be innovative, but to be there, in Europe, where Trump can't touch them.)

There are incredibly cool, novel designs in Europe. But they can't see the light of day because these duplication projects soak up funding. (Again, as they probably must.)