Alias vs Shared Mailbox

Below is a comparison of Alias versus Shared Mailbox. 

It is important to determine which type to create before actually creating them. Once the Alias has been created, and emails have been received in the Alias, it will not be easy to convert Alias to Shared Mailbox - migration of email will be involved.  

To create an Alias:

Login to Microsoft 365 admin center > Users > Active Users > go to the user which you will be creating the Alias under > Aliases > Manage username and email > add the Alias > Save changes.

To create a Shared Mailbox:

Login to Microsoft 365 admin center > Teams & groups > Shared mailboxes > Add a shared mailbox > Save changes. 

After the Shared Mailbox has been created, users who need access to the Shared Mailbox must be added as "Members" to the Shared Mailbox.