I believe the Orly collection was available first but that said there are some interesting dupes in the Orly collection.
It really looks like an exact dupe in both the flash shot above and natural light shot below:
Even though my particular MAC mean & green has a crap brush (the bristles stick out in different directions) I would still recommend the Orly over the MAC polish due to its thinner but more consistent formula and longer brush (with a sturdier handle). Also I believe the Orly is slightly cheaper and you get 18mL/0.6Fl Oz as opposed to the 10mL/0.34 Fl Oz for the MAC. Honestly I don't know why I keep buying MAC nail polishes! That said Orly does chip easily... but so do most brands :-D