A C-band dish (often given as BUD, for "big ugly dish") is a colloquial name for a TVRO satellite dish used to receive satellite television signals from FSS-type satellites on the microwave C band. BUDs are usually 6½ to 12 feet or two to 3.5 meters in diameter, and have been a source of much consternation (even local zoning disputes) due to their perception as an eyesore. Neighborhoods with restrictive covenants usually prohibit this size of dish, except where such restrictions are illegal.[1]
Ku band is primarily used for satellite communications, most notably for fixed and broadcast services, and for specific applications such as NASA's Tracking Data Relay Satellite used for both space shuttle and ISS communications. Ku band satellites are also used for backhauls and particularly for satellite from remote locations back to a television network's studio for editing and broadcasting. The band is split into multiple segments that vary by geographical region by the International Telecommunication Union (ITU). NBC was the first television network to uplink a majority of its affiliate feeds via Ku band in 1983.
all current dth transmission services are transmitted on ku band.... ku band has smaller size dishes
source : wikipedia