There are some A and some B brands, yes.
Some manufacturers use the reference layout from nVidia for the card-design,
others develop their own designs which can have advantages.
Some add video decoders, some not; others use cheaper condensers, others better,
some overclock their cards, some not, (to be continued...)

Personaly, I wouldnt go with the cheapest, but anything above midrange is mosttimes ok.