What is the difference between these two blocks? What does “broadcast and wait” wait for?

broadcast [ v]
broadcast [ v] and wait

The first one starts the scripts in all the other places that have a receiver for the broadcast. The second does that but then it waits until all those scripts have run to completion before it gets to the next step.

Thanks Guys!

i am new to ‘scratch’.
is there a list of all the internal broadcast messages that occur and when they occur?

i keep seeing ‘start game’ message as a receipt from a broadcast but i do not know who initiates this message

thanks for any help..