So what is the difference?

[WindowMaker]

So I look at something like this

http://www.reefshops.com/sunsun-jvp-...tion-pump.html

I see a Hydor pump (oh look, they even mention it in the description). I understand that some people will feel that this is probably some knockoff. But the reality is that most of the time the "knockoff" is coming from the same factory.

Any opinions on what the worst that could happen is?