Dendrobium tenellum vs pseudotenellum - how to distinguish?

I purchased Dendrobium tenellum from a reputable grower, and after googling it, and being sent here :-) i question the identity of the plant. Some pictures of D. tenellum show more substantial terete leaves while pseudotenellum has very fine terete leaves. And IOSPE shows a bit of purple in tenellum, while pseudotenellum is pure white.

Is that the only difference? Or how can I tell the difference? My concern is really about growth conditions. IOSPE shows slightly different conditions for the 2.

I appreciate any advice!