Ricoh WG-50 has a 16.0MP 1/2.3" (6.17 x 4.55 mm ) sized BSI-CMOS sensor . On the other hand, Panasonic ZS50 has a 12.0MP 1/2.3" (6.17 x 4.55 mm ) sized CMOS sensor .
Below you can see the WG-50 and ZS50 sensor size comparison.
Ricoh WG-50 and Panasonic ZS50 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 Panasonic ZS50 has 32% larger pixel area (2.34µm2 vs 1.76µm2) compared to Ricoh WG-50, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.