Anyone know the difference between the Godox QS-400 and GS-400?
Specs look the same (other than weight), and price is about the same (QS-400 $216, GS-400 $202).

If I had to guess, I would say that Godox switched suppliers or designs.  I don't believe they make their own lights - almost nobody in that price range does.  Usually some company in China or wherever makes a million of something, and then Godox, Cowboy Studio, etc. contacts them and asks for X amount with their name on them.

I suspect that they couldn't get as many lights as they wanted from the same series/manufacturer, so they bought some from Supplier A and some from Supplier B.  Happens all the time.

The only difference I can see is that one light is a bit heavier and has a handle on the back, where it's more useful.

They're both part of a new lineup they've recently added. The QT series (the most expensive of their new line) has been compared with Einsteins, and have pretty good reviews.
http://flashhavoc.com/godox-qt-600/

Godox is the manufacturer, they rebrand for several companies (Neewer, Cowboy Studio, Cheetah Light, etc).

Fair enough.  In that case, it might be the opposite of what I said.  It's possible that Godox makes lights under Spec A for one company and Spec B for another company, so they just decided to sell both types themselves under their own name.  Why not, right?