Laravel 5.1: Difference between Event and Mail:queue?

I have registration form where I want to send an email to users after they register successfully. I want to run email in background so that page's response time is a bit better.

For email in background, I saw that we can use:

• Event with ShouldQueue
• mail::queue() method.

My question is that in the context of queuing email, what the difference between above two methods ?

via Chebli Mohamed