Olympus SZ-30MR has a 16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CMOS sensor and features TruePic III+ processor. On the other hand, Sony W550 has a 14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor and features BIONZ processor.
Below you can see the SZ-30MR and W550 sensor size comparison.
Sensor Size and Resolution Comparison image of Olympus SZ-30MR and Sony W550 Cameras
Olympus SZ-30MR and Sony W550 have sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture. On the other hand, since Sony W550 has 14% larger pixel area (2.01µm2 vs 1.76µm2) compared to Olympus SZ-30MR, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.