Panasonic ZS7 has a 12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor and features Venus Engine HD II processor. On the other hand, Samsung HZ50W has a 14.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor .
Below you can see the ZS7 and HZ50W sensor size comparison.
Panasonic ZS7 and Samsung HZ50W 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 ZS7 has 16% larger pixel area compared to Samsung HZ50W, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.