FujiFilm S2800HD has a 14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Panasonic ZS40 has a 18.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CMOS sensor and features Venus Engine processor.
Below you can see the S2800HD and ZS40 sensor size comparison.
FujiFilm S2800HD and Panasonic ZS40 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 FujiFilm S2800HD has 30% larger pixel area compared to Panasonic ZS40, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.