Panasonic ZS60 has a 18.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CMOS sensor and features Venus Engine processor. On the other hand, Olympus XZ-10 has a 12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor .
Panasonic ZS60's sensor provides 6MP more than Olympus XZ-10's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
Below you can see the ZS60 and XZ-10 sensor size comparison.
Panasonic ZS60 and Olympus XZ-10 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 Olympus XZ-10 has 52% larger pixel area (2.38µm2 vs 1.56µm2) compared to Panasonic ZS60, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.