Nearby Connections supports different strategies for advertising and discovery. The best strategy to use depends on the use case.
Cluster
The cluster strategy is a peer-to-peer strategy that supports an M-to-N, or cluster-shaped, connection topology. In other words, this enables connecting amorphous clusters of devices within radio range (~100m), where each device can both initiate outgoing connections to M other devices and accept incoming connections from N other devices.
This strategy is more flexible in its topology constraints than the star strategy, but results in lower bandwidth connections. It is good for use cases with smaller payloads that require a more mesh-like experience, such as multiplayer gaming.
Star
The star strategy is a peer-to-peer strategy that supports a 1-to-N, or star-shaped, connection topology. In other words, this enables connecting devices within radio range (~100m) in a star shape, where each device can, at any given time, play the role of either a hub (where it can accept incoming connections from N other devices), or a spoke (where it can initiate an outgoing connection to a single hub), but not both.
This strategy lends itself best to situations where there is one device advertising, and N devices which discover the advertiser, though you may still advertise and discover simultaneously if required.
This strategy is more strict in its topology constraints than the cluster strategy, but results in higher bandwidth connections. It is good for high-bandwidth use cases such as sharing a video to a group of friends.
Point-to-Point
The point-to-point strategy is a peer-to-peer strategy that supports a 1-to-1 connection topology. In other words, this enables connecting devices within radio range (~100m) with the highest possible throughput, but does not allow for more than a single connection at a time.
This strategy lends itself best to situations where transferring data is more important than the flexibility of maintaining multiple connections.
This strategy is more strict in its topology constraints than the star strategy, but results in higher bandwidth connections. It is good for high-bandwidth use cases such as sharing a large video to another device.