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, Olympus E-M5 II has a 16.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features TruePic VII processor.
Below you can see the FZ1000 and E-M5 II sensor size comparison.
As seen above, Olympus E-M5 II 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.