Customer Registration --> send email method --> transactional vs direct

Jeff Guynn

I notice on the backend customization setting: settings --> customers --> Registration, we can select whether to send the registration confirmation email as "transactional" or "direct".

I understand the logic here. Usernames, passwords, registration info (i,e, non-marketing messages) are typically sent as a transactional email.

Curious about 2 things here:
(1) Why, in this case, would I select anything other than "transactional"?
(2) How does MW communicate this choice to my mail sender (i.e. Mailgun, etc.)? In other words, what impact does my choice in these settings have on my account with a 3rd party sender? Does this choice indicate that MW will try to find one of my senders that has a "transactional" sending method and use that one in this case?

Thanks for the cllarification.
That "transactional" is reffering to the mailwizz's feature of sending transactional emails, it doesn't care about what services you are using for sending emails.
So transactional means to queue the email and send it later when the cron job for sending transactional emails is running, and direct means to send them immediatly.