BLUETOOTH SPECIFICATION Version 5.0 | Vol 1, Part A page 253
The Broadcaster role is optimized for transmitter only applications. Devices
supporting the broadcaster role use advertising to broadcast data. The
broadcaster role does not support connections. The Observer role is optimized
for receiver only applications. Devices supporting the observer role are the
complementary device for a broadcaster and receives broadcast data
contained in advertisements. The observer role does not support connections.
The Peripheral role is optimized for devices that support a single connection
and are less complex than central devices. Devices supporting the peripheral
role only require Controllers that support the Controller’s slave role. The
Central role supports multiple connections and is the initiator for all
connections with devices in the peripheral role. Devices supporting the central
role require a Controller that support the Controller’s master role and generally
supports more complex functions compared to the other LE GAP roles.
BLUETOOTH SPECIFICATION Version 5.0 | Vol 1, Part A page 253