What's the difference between an Office 365 group and a distribution list?
A distribution list is a set of email addresses. You can use the distribution list to send an email message or meeting invitation to all the addresses at once. An Office 365 group includes a distribution list but also includes a shared:
• Inbox for group email communication
• Calendar for scheduling group meetings and events
• Library for storing and working on group files and folders
• OneNote notebook for taking project and meeting notes
When you join a group, your email address is automatically added to the distribution list and you gain access to all group information. You don't have to wait to see group email or view a shared document. You join, you have access to everything, from everywhere: in the cloud, on the desktop, or on a mobile device.