They have a few distinctive elements that differentiates them from:
1) Thicker stems is a good differentiator. They have a much thicker stem than those found on Dendrobium orchids;
2) The closed bud of a bloom is quite small and round, unlike the Dendrobium which is larger, more elongated and 'bell shaped' at the base.
3) The petals on each bloom are often broader and fleshier than that found on a Dendrobium orchid. Mokara's are great for earthy and bright coloured arrangements (a lot of red, orange yellow, strong purple and pink varieties).
This post is part of the Floral Friday Fotos meme.