The sponsor FxPro and the Watford crest are larger in the Original shirt.
The Watford crest is a bit darker and longer in the Fake ones.
The sponsor FX Pro is darker on the Fake shirts. The Adidas logo is always at least quite deformed on the Fake shirts.
The logo “climalite” is put on the right bottom on the Fake shirt, while it's actually on the right side in the Original one.