A message in a conversation is initiated by either you or your booker. Pro users have the ability to create message templates that can be employed for further speed and efficiency.
Emails are system generated messages that are automatically sent in response to a specific action. For example, when you select Sign & Send Proposal the system automatically sends the Proposal Sent to Client email to the contact listed on the event. Pro users can edit the language for these emails. Lite users can not.