I've been using Tretinoin to open up my pores and even up my pigmentation, Are red marks considered Acne Scars and if not, what are considered Acne Scars?

It will, but you may need to use it for 2 or 3 months or even longer to get rid of the marks completely. Tretinoin is supposed to help with red marks too.

I've been using Tretinoin for 6 weeks now and have noticed a slight improvement, I'm sure I haven't given it proper time for anything dramatic though, but I will likely look into getting a series of chemical peels done.