Panasonic FZ1000 has a 20.0MP 1" (13.2 x 8.8 mm ) sized CMOS sensor and features Venus Engine processor. On the other hand, Panasonic GX7 has a 16.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features Venus Engine processor.
Below you can see the FZ1000 and GX7 sensor size comparison.
As seen above, Panasonic GX7 has a 1.9x Larger sensor area than Panasonic FZ1000. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.