No they are not !
http://www.phoenixautobulbs.co.uk/st...0mb8btkrujo073 Just look at this link, the big difference is not only the corded connector, but the depth of the focal point within the lens.
You may be able to get an H3 into the housing of an H1, but the light will be out of focus, and considerably less effective.
As for manufacturers, well, you pays your money etc
My preference is for the kits sold by autolamps-online. Not the cheapest, but I've fitted several kits and never had a problem.
I have them fitted to both high and low beams on the ST, and wouldn't go back to standard - I can actually see the road at night now !
