The three are so similar.. I don't know much on the WZ-X, but the GJ-X and CH-7 both have a stealth design, flying-wing configuration and comparable operational profile, so I guess what I'm trying to figure out is what makes the WZ-X distinct enough from the CH-7 that it would be classed as an entirely new variant.
Both the CH-7 and WZ-X are ISTAR UAVs with VLO and excellent endurance capabilities.
Differences:
1. The WZ-X is much, much larger than the CH-7. The WZ-X is almost as large as the B-2, whereas the CH-7 is only about half the size at most.
2. The WZ-X has a pure flying wing design configuration, whereas the CH-7 has a cranked-kite design configuration.
3. The WZ-X has a much superior VLO capability than the CH-7 in the latter's present configuration. Those slanted vertical stabilizers seen on the CH-7 are large RCS raisers when viewed from the sides.
4. Thanks to their respective sizes, the WZ-X should have exceptional endurances, possibly with intercontinental-range capabilities. In contrast, the CH-7 could only achieve 2IC-ranges/radius at most.
5. The WZ-X is already undergoing trial and evaluation process with the PLAAF at Malan, whereas the CH-7 is developed as a private effort by CASC (with no signs of the CH-7 being planned for procurement by the PLAAF).
On the other hand, the GJ-X is a B-21-sized UCAV with an obvious cranked-kite design configuration. The GJ-X should be a VLO strike platform, possibly with intermediate/intercontinental-range capabilities. The GJ-X is completely different from both the WZ-X and CH-7 in terms of expected roles and missions.