There are several key features that will differentiate your mailbox once it is migrated to Exchange Online:

• Exchange Online will give you 50GB of storage in your primary mailbox as well as an additional 100GB of storage in your Online Archive mailbox. The older mailboxes are set to a 3GB quota and utilize Enterprise Vault for 3rd party archiving.
• Content in your primary mailbox will be moved to your Online Archive after two years unlike Enterprise Vault archiving which archived content after 90 days.
• All mail will be hosted in Microsoft’s Government Cloud instead of on-premise servers. Microsoft’s cloud architecture guarantees 99.9% uptime and world-class data security.
• You will use your UPN (email address) as your username to log in to Exchange Online instead of “domain\username”.
• Logging in to Exchange Online outside of the state network will require Multi-Factor Authentication to further enhance security for your account. This security feature greatly reduces the risk of your account being compromised by outside forces.