Nikon P530 has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor . On the other hand, Nikon P500 has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features Expeed C2 processor.
Below you can see the P530 and P500 sensor size comparison.
Nikon P530 and Nikon P500 have the same 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 Nikon P500 has 32% larger pixel area (2.34µm2 vs 1.76µm2) compared to Nikon P530, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.