Double Side-band Amplitude for Radio Transmission & Single Side-band Reduce Carrier for Point-to-point Transmission
Double sideband amplitude modulation is used for broadcast and other radio transmission because it's been grandfathered in since the start of radio, being the first technology used to generate a variable amplitude RF carrier.

Single-sideband reduced carrier modulation is used to reduce the bandwidth of the transmitted signal without affecting its information content while - for the same power input to the final amplifier -  increasing the power used to transmit data, both of which serve to increase the signal-to-noise ratio in whatever medium the transmission is occurring.