Panasonic FX78 has a
12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor and features Venus Engine FHD processor. On the other hand, Panasonic F5 has a
14.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor .
Below you can see the FX78 and F5 sensor size comparison.
Panasonic FX78 and Panasonic F5 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 Panasonic FX78 has 16% larger pixel area compared to Panasonic F5, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.