In the series which has the unofficial crossover, an unusual rift in space leads into an alternate fluid hyperspace that is described exactly like the Babylon 5 hyperspace. And the ships in there - which are from the crossover species - are mostly organic living things. Both concepts are nearly unique for the series that has the crossover.
Hope that helps a bit

PS.: Commander McLane is correct, english is not my mother tongue. But both series - ha, also a hint - at least also exist in german.