Campy uses wider bearings in the lower race. Hence the two bearing sizes.

Tange, the one you checked out, has only one size.

btw Campy and some higher end Shimano had the best bearing errr holder things (ring of metal, cut outs for bearings). If you're not using loose bearings, one of those is the way to go. You can tell because the bearings are almost touching. If you take a look at the Tange headset, there's a gap between each bearing in the RETAINER. RETAINER, it's a bearing retainer. I just remembered it.

I feel like the blue fish in Nemo. I can't remember her name though.

hope this helps,
cdr