Olympus E-M10 IV has a
20.0MP Four Thirds (17.4 x 13 mm ) sized CMOS sensor and features TruePic VIII processor. On the other hand, Panasonic GH4 has a
16.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features Venus Engine IX processor.
Below you can see the E-M10 IV and GH4 sensor size comparison.
Sensor Size and Resolution Comparison image of Olympus E-M10 IV and Panasonic GH4 Cameras
Olympus E-M10 IV and Panasonic GH4 have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Olympus E-M10 IV
or the
Panasonic GH4 ,
including hyperfocal distance.