In a baseband transmission, the entire bandwidth of the cable is
consumed by a single signal. In broadband transmission, signals are
sent on multiple frequencies, allowing multiple signals to be sent
simultaneously.
Also
Baseband Signalling:
1)Uses digital signalling
2)No frequency-division multiplexing
3)Bi-directional transmission
4)Signal travels over short distances
Broadband Signalling: 1)Uses analog signalling
2)Unidirectional transmission
3)Frequency-division multiplexing is possible
4)Signal can travel over long distances before being attenuated