I've always assumed it was more powerful than the Federation. Balok had to come from some context, after all, and that's a huge and powerful ship designed to do...what, exactly?
Possibly the same stuff the Narada was built for. A big ship with a powerful tractor beam and no known weaponry would be nice for tearing apart asteroids.... Although tentacles work better than bubbles in conveying that impression.
But a cluster of bubbles capable of detaching smaller clusters of bubbles could also be a container transport, with economy advantages from size.
Timo Saloniemi