I dont know what the "H" stands for...but the "A" typically stands for the impeller size...."A" is pretty much a standard size.

There is no significant difference between a 12jb and a 12jc pump suction housing. they can be changed out. 12jb's did come with a split bowl and the 12jc came with a 1 piece bowl. they are compatible between the 2 suction housings.

I have a 12jc-a-h   

I burned up my 12jb-a pump. I have this 12jc-a-h. I can't find anyphysical difference
does anyone know what the "a" and the "h" stand for? Any info would be much appreciated.
thanks guys