Airsoft GALIL difference?
 

How can you tell the difference between king arms, cyma, ics, cybergun, etc Galils? Are they all just rebrands and made by one manufacturer or?

Well typically each company uses different components or parts for their version of AEG's. Different internals, different externals, different materials, different QC. Obviously some are rebranded manufacturers, but at least some are unique to the company.

Maybe someone else can weigh in on what they know of Gali's?

ICS is a Taiwanese manufacturer
CYMA is a Mainland China Manufacturer
Cybergun is a French rebrand/ Trademark licensing company
Kingarms is a Hong kong based Manufacturer

They are all completely different, and most external parts are not interchangeable. I currently own an ICS Galil AR and a KA Galil SAR. The KA is the more TM compatible between these two.