On May 12 Work or School Accounts were enabled in Community, along with Microsoft accounts (MSA). This allows you to seamlessly navigate between the Community, Dynamics 365 applications and Azure Active Directory enabled sites while logged into your Work or School account. If you prefer to continue using your Microsoft account in Community, you will still have that option as well.
In case you would like to migrate your community content (username, badges, forum/blog posts, etc.) from your Microsoft account to your Work or School account, a self-service tool was released on May 12 which migrates all community content from one login to another. More information about this process is available here: https://community.dynamics.com/w/help/146.multiple-community-accounts
If you have two logins with separate community accounts, you can request to have them merged by sending an email to firstname.lastname@example.org - information about this process is available now on the same page: https://community.dynamics.com/w/help/146.multiple-community-accounts
When logged into a Work or School account, the default profile icon will look slightly different: