Canon 60D has a 18.0MP APS-C (22.3 x 14.9 mm ) sized CMOS sensor and features Digic 4 processor. On the other hand, Canon 50D has a 15.0MP APS-C (22.3 x 14.9 mm ) sized CMOS sensor and features Digic 4 processor.
Below you can see the 60D and 50D sensor size comparison.
Canon 60D and Canon 50D 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 (22.08µm2 vs 18.54µm2) compared to Canon 60D, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.