Hubs are differentiated from switches in that between the two, only hubs have:

A hub is a Layer 1 device that repeats all incoming signals to every port, making all ports part of the same collision domain. Only one device can transmit at a time across the entire hub without causing a collision, which is the defining characteristic that distinguishes a hub from a switch.

Both hubs and switches are Layer 2-adjacent devices that by default belong to a single broadcast domain, so this is not a differentiating characteristic of hubs alone.

Multiple collision domains are a characteristic of switches, not hubs - each switch port isolates its own collision domain.

Multiple broadcast domains require a Layer 3 device such as a router, or VLANs configured on a switch - neither hubs nor standard switches provide this.