sedumzz said: I am having a hard time identifying the differences between different "velvet philodendron"(?)
Maybe it's because I've never felt them or noticed anything on the petioles 
Yes they can be very look a like, if you can see them on flesh, and touch them, they are really different, details, texture, and all.
P. luxurian has round, very thick, fleshy petioles, smooth, no hair at all. back of leaves reddish especially on young. They really are velvety on touch, and kind of fleshy leaf blade.
The color perhaps bit similar with P. El Choco Red ( P. Rubrijuvenilum). but in my opinion P. El Choco Red is not so velvety at touch, thin leaf blade. The Petiole bit warty, thinner but sturdy
Also, smaller plant sometime are very difficult to distinguished, Some bad seller use this to trick buyer.
