One Time Email > This is what you would use to communicate important information to your players, volunteers and others. It can also be used post-event for things like sending a 'thank you' to all those who made the event a success or a summary email on event highlights (congratulating hole-in-one contest winners, achieving or exceeding a donation goal...)

Player Registration Email > These are designed to help you get contacts to register for your event. When you are setting up this email, you will have the option to set a reminder date for the email to be sent out a second time. This email type will automatically check your player registrations each time to ensure you aren't emailing a contact that has already registered.