DIFFERENCE BETWEEN KU AND CBAND LNB.

Ku-band permits the use of smaller antennas that are aesthetically better and much cheaper than C-band.
A typical Ku-band antenna ranges from about 50cm to 1.2m and a typical C-band antenna ranges from 1.5, 1.8m, 2.4m, 3.8m etc.
Ku-band requires less radio power than C-band to provide the same signal strength thus allowing a smaller antenna.


The cost of C-band equipment and installation is much more than that of Ku-band
C-band transmits at a lower frequency ( around 4 MHz), while Ku band transmits at about 11 to 12 GHz.

C-band dishes usually come with a larger size than Ku-band satellite antennas.

Some satellites transmit both C and KU band frequencies. E.g Intelsat 7/10, therefore for one receive channels from the two frequencies, one needs a big dish that will be able to work with the C band signal and as well work for the KU signal.
The person can then choose to either provide two lnbs for the two signals or purchase a universal lnb that can receive signals across the C band and KU band frequencies (have not used that type myself).

For people who always ask, the whole thing is like the VHF and UHF TV signals we use to deal with back in the days.
TVs back then used to have separate knobs for tuning VHF and UHF frequencies until the white decided that everything should be pressed with button and that left a lot of younger folks not knowing anything about frequencies of TV channels they watch everyday.