Canon 50D has a 15.0MP APS-C (22.3 x 14.9 mm ) sized CMOS sensor and features Digic 4 processor. On the other hand, Canon 60D has a 18.0MP APS-C (22.3 x 14.9 mm ) sized CMOS sensor and features Digic 4 processor.
Below you can see the 50D and 60D sensor size comparison.
Canon 50D and Canon 60D 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 Canon 50D has 19% larger pixel area compared to Canon 60D, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.
DxOMark Sensor Scores
DxOMark is a benchmark that scientifically assesses image quality of camera sensors. It scores camera sensors for color depth (DXO Portrait), dynamic range (DXO Landscape) and low-light sensitivity (DXO Sports), and also gives them an overall score. Canon 50D and Canon 60D sensors have been tested by DxO and the results show that 60D has a better overall score of 66, 3 points higher compared to 50D's score of 63.