There are several differences between IS-IS Hello packets used on broadcast interfaces and on point-to-point...

On broadcast interfaces there are different Hello packet types for level-1 and level-2 adjacencies, whereas on point-to-point interfaces there is a single Hello packet type.

The multicast MAC addresses to which the Hello messages are sent are different on broadcast interfaces and on point-to-point interfaces.

The neighbors are identified using their interface MAC addresses on broadcast Hello messages and using their system IDs on point-to-point Hello messages.

Broadcast Hello messages identify the elected designed IS (DIS) and point-to-point Hello messages do not.