Both of them are rather new rifles, so it may be hard to tell yet, your best bet is to google reviews for both and read what people say. I've always been a fan of CA bodies, not the internals much, but those were older versions. I've really liked what G&G I've handled, though I've never handled one.
I can't seem to find a review on either right off the bat, but like I said they are new.
From first sight, the G&G only sells a long barrel version for $500
Yet the CA sells both a long and short barrel version for $460 and $445 respectively.
Now before other swoop down on your, 5 minutes of searching yielded those results, so if you search first before you ask, then you may not annoy people.
Anyways welcome to the forum, make yourself an intro post and read the rules and you'
ll be good to go.