Olympus E-PL7 has a
16.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features TruePic VII processor. On the other hand, Samsung NX300M has a
20.0MP APS-C (23.5 x 15.7 mm ) sized CMOS sensor and features DRIMe IV processor.
Below you can see the E-PL7 and NX300M sensor size comparison.
As seen above, Samsung NX300M has a 1.6x Larger sensor area than Olympus E-PL7. 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.