Exchange Administration Center:-No Exchange Management console in exchange 2013, it is all new Admin center.
Exchange architecture revisions: Exchange 2007 and 2010 are has five server roles, mainly to address performance issues like CPU performance, which would suffer if Exchange were running as one application. But Microsoft has improved a lot on the performance side, so Exchange 2013 has just two roles 1) Client Access server role 2) Mailbox server role. The Mailbox server role includes all the typical server components (including unified messaging), and the Client Access server role handles all the authentication, redirection, and proxy services. You can deploy Exchange 2013 with an Exchange 2010 Edge Transport server role but a 2013 Edge role is planned post-RTM.
A new managed store: This new feature of higher availability and resiliency, it doesn’t mean the ESE (Extensible Storage Engine) database engine has been replaced with SQL (who knows it may in future release) . Exchange 2013 continues to use ESE as the database engine. But now each database runs in its own dedicated worker process, so a hung process in one database will not cause problems in other databases. Fast Search (an add-on to SharePoint 2010) is also integrated into the managed store for improved search and indexing.
Modern public folders: Rather than just getting rid of public folders (something promised for future releases), Microsoft has embraced them once again. They are no longer managed through the separate Public Folder Management Console; instead, they are managed via the EAC. That makes them public folder mailboxes, which means they use regular mailbox databases. In turn, this means they can be made part of a database availability group for disaster recovery.
DLP (data loss prevention): DLP is new in Exchange 2013’s transport rules, but it’s also a continuation of Mail Tips in that it warns users when they may be violating policies meant to prevent disclosure of sensitive data. Such disclosures are usually inadvertent, so the use of DLP-fired reminders lets users be aware when they are putting something like a credit card number or Social Security number in an email. The built-in DLP policies are based on regulatory standards like PCI.
Outlook Web App enhancements: The whole of OWA is redesigned, One awesome feature is support for offline access, which lets users write messages in their browser when offline, then have the messages delivered when they connect to the Internet. There’s also a new set of UI layouts that users can choose from for desktop, tablet, and smartphone use — a smart approach.
Server Roles: Microsoft Exchange Server 2013 Preview consists of the following two server roles Client Access server role and Mailbox serverrole, RPC is no longer a supported direct access, This means that all Outlook connectivity must take place usingRPC over HTTPS (also known as Outlook Anywhere).mailboxes to store both the hierarchy and the public folder content. This new design also means that there is no longer a public folder database. Public folder replication now uses the continuous replication model.
Exchange 2013 now made up of several different services: the Front End Transport service on ClientAccess servers, the Hub Transport service on Mailbox servers, and the MailboxTransport service on Mailbox servers. For more information