Mail and Send Mail Plugin

What is the difference between Send mail and Mail plugin?

Send Mail plugin can be used when you want to send a mail from user credentials & server details which are mapped on AE-Server under SMTP settings. These credentials & server details will be utilized only when you execute the process from AE server/portal and not from Process Studio.

Mail step/plugin in workflow/process is used when you want to trigger mail by using any different users credentials along with different server details, formatting mail body etc.