Board Thread:Character Discussion/@comment-25106811-20140910001139/@comment-24674051-20140910184110

I think the whole point of Zelena is that she was Literally Green with envy. She not only was jealous of Regina, she deeply desired to have everything that Regina had (Good, Bad, and otherwise). Also, her magic is probably an order of magnitude stronger than Regina's, so it's manifestation would naturally be more obvious.

And I wouldn't say that Regina was jealous of Snow's happiness. She just had a long lasting, deep rooted anger at Snow because of what happened with Daniel. Her emotional response, though prolonged and deep, was nowhere near as intense as Zelena's. For the longest time, Regina at least had her Dad to somewhat hold her emotions in check (amazing what even a little love can do). Then she had Henry. Her Mom, for all of Cora's flaws, did NOT abandon Regina. And even Snow tried many times to get beneath the surface of Regina, and tried to accept her. Snow never hated Regina, though she did get quite upset with her at times.

Zelena, on the other hand, had been abandoned by her Mom, never know her dad, was rejected by her adoptive dad, was rejected by Rumple, and even ultimately rejected by Glinda and the other witches. She was truly alone and bitter, and her anger, jealousy, and envy did not have anything positive to balance it out. And when her negative emotions had nothing to balance them out, they manifested themselves in a visible fashion.

That's my opinion, anyway.