Broadcast vs group
A broadcast sends each person a private message; a group is one shared chat where everyone sees everyone.
In a WhatsApp group, every member sees every message and every phone number, and replies pile up for everyone. A broadcast sends the same message to each person privately, and replies come back only to you.
The WhatsApp Business app’s broadcast lists stop at 256 people and only reach those who saved your number. On the WhatsApp Business Platform, broadcasts have no such limit, and everyone receives them.