O365 Distribution Groups provide the functionality to send email to large groups of people at once whilst also allowing owners to set moderation and restrictions on who can send to the list of members within that group.
See the links to all these articles in the 'Related Articles' section
A Team provides instant messaging communication and file storage, making it much more effective for daily communication and collaborative work than a Distribution Group.
A Distribution Group is only used for sending emails to a group of people. They are most useful when you need to broadcast information to a specific group of people.
Please see the 'What is Microsoft Teams' article for more information on Microsoft Teams.