The sensor size and the body size both are different, Sony A77 II features large 24.3MP APS-C Exmor CMOS Sensor and with it bigger sensor size on the other hand the E-M5 features 16 MO 4/3 based sensor…
Sony a77II vs. Olympus OM-D E-M5 Specification Comparison Table.
Megapixel: The Sony a77II features more resolution compared to Olympus OM-D E-M5, more resolution gives you ability to recompose your images and also to grab out high-quality print-outs.
Bigger Sensor Size: Sony a77II have bit bigger sensor size compared to Olympus OM-D E-M5, bigger sensors captures more light and have better color depth, improved noise performance and increased dynamic range.
Image stabilization: Both camera features in built body image stabilization system, but the Olympus features built in 5-axis image stabilization system.
AF System: The Sony A77 II have blazing fast HYBRID AF System, on the other hand the E-M5 also have bit twisted F.A.S.T contrast detect AF System, the contrast detect AF system of contrast used in E-M5 is 2X faster than conventional contrast detect camera, but slower than Sony A77 II.
More AF Points: Sony a77II Fast Hybrid AF system uses a total of 79, so we have no doubt that Sony a77II will do more quick and precise AF than Olympus OM-D E-M5.
Better low light performance – The Sony a77II have more ISO range compared to Olympus OM-D E-M5, the Sony a77II features more ISO range hence you get better low-light images at HIGH ISO range.
Video Mode: Sony a77II features full HD video recording @ 60 and 34 fps frame rate.
Supported formats Sony a77II Full HD videos are recorded using the high-quality AVCHD codec, supported in the Internet-friendly MP4 format.
Video Mode: Olympus OM-D E-M5 features full HD video recording @ 60 frame rates.
Supported formats Olympus OM-D E-M5 MOV format (MPEG-4 AVC/H.264).
Sony a77II features 3″ Rear Screen Swivel LCD (1,228,800) (screen dots) on the other hand Olympus OM-D E-M5 have Tilting 3″ Rear Touch screen Tilting LCD (610,000 screen dots), so we get more flexibility while composing our shot with Sony a77II.
Wireless: The A77 II features built in wireless and NFC connectivity, So Sony have better connectivity options.
Battery Life (CIPA): Sony a77II battery rating is 480 shots and other hand Olympus OM-D E-M5 battery rating is 360 shots. According to CIPA.
Dimensions: Olympus OM-D E-M5 is smaller than Sony a77II.
Weight: Olympus OM-D E-M5 lightweight than Sony a77II.
High ISO Test Between Sony a77II vs. Olympus OM-D E-M5
Verdict: The Sony A77 II do have advance core specification but we don’t see any major difference in image quality, at the end you get very FAST AF and continuous shooting mode with A77 but if care about price and size go with E-M5