One more question about orchid names

Hello,

There is this paph:
Paphiopedilum delenatii forma albinum

and this phal:
Phalaenopsis violacea var. alba

In both cases flower is white.

Why in first name it is forma but in second - variety?

Thanks

[ronaldhanko]

As I understand it, a variety is a significant and established variation of a species and often a definite geographic range, while a form is a less significant variation often just a variation of color or size. In the trade, however, most variations are simply referred to as varieties.

[Ray]

I don't know how "universally accurate" it is, but check this out:
Plant Classification

Thanks a lot!