Who says that leaves are green

[Fae]

First thing, I absolutely love the overall message of this poem. It touches on how each individual human experience is unique. The dualistic elements are also something I am a fan of, and a theme common in my own works as well.

Now for a bit more of a breakdown. (Bear in mind, I've not really critiqued poetry before, so I'm rather unsure of what I'm doing, so alot of this will be based on personal preference rather than what would be right in a technical way, but I'll give it my best!)

Who says that leaves are green
Or sky is blue? <--- I would have changed the location of the word "that." Like... "Who says leaves are green, or THAT the sky is blue

Who says that days are always light
Or night is immanently dark? <--- I'm not sure if you meant inherently or imminently here, but I suspect it's the former rather than the latter.
 
Who says what anything is really like? <--- I'd personally either remove this, or change it so something like "who defines what anything means?"

Who says I have to be like you?
Who says you have to be like me?
For your green may be my blue
My light may not be light for you <--- I'd go with "That light may not be light for you."
 
… and my colors change as seasons go. <--- I'd expand on this and place it elsewhere in the poem

As I said above, I really like the overall concept and theme of opposites here. There's so much you can do with the subject matter you're talking about, and I'd continue along this as a theme for future works. I hope I've been helpful!

Warmly,

Fae.