As mentioned before, Ku band uses dishes from 35cm up to 1.5mtrs on average. These dishes are solid and not mesh. The stronger the signal at your location, the smaller the dish you will require.
Frequencies for Ku band are 12Ghz to 18Ghz, however, most satellite transmissions are closer to the 12Ghz section of the band.
C band uses both solid & mesh dishes. Solid dishes have more gain (signal amplification), mesh dishes less wind loading. These dishes are mostly used for signals that cover vast areas of Asia etc. and have a massive footprint.
Frequencies for C band are 4Ghz to 8Ghz, however, most satellite transmissions are closer to the 4Ghz section of the band.
Some transponders transmit on frequencies below the recognized band parameters but it is still classed as Ku or C band.