Server Side Changes from Lync Server 2010
Management and Administration Changes – Changes in RBAC for Persistent Chat Manager and Response Group Manager roles, Persistent Rooms Management now manageable from within Lync Control Panel and PowerShell, Lync Administration through Office group Policy Templates
Server Roles Consolidation – Only 3 server roles – Front-End, Edge & Persistent Chat Server.
Archiving and Monitoring Roles now part of Front-End Servers – No more separate role or server. A/V Conferencing Server is also now always collocated with Front-End Server Role.
Better High Availability and Disaster Recovery Architecture with Pool-Pairing providing Active-Active Failover – Metropolitan Area Resiliency and Active-Passive Pool Pairing no more supported. Instead 2 pools are always paired in an Active-Active mode.
Support for SQL Mirroring for Back-end Databases – Now supported on SQL Server 2008 R2 and 2012 for Database Mirroring (AlwaysOn feature not supported)
Tighter Exchange Integration – Unified Contact Store (UCS) with Exchange 2013 as Backend Contact Store. Lync Server 2013 also supports archiving user data on Exchange 2013 in place of SQL archiving.
Improved Conferencing Features and PowerPoint Sharing – Join Launchers now supported on Windows Phone 7, Android devices, Apple iOS devices, Windows 8 and Internet Explorer 10. Now higher image quality with Office Web Server as rendering engine in background, independent slide browsing from mobile devices and web browsers.
Enhanced Video Conferencing Features – All New Gallery view now support up to 5 concurrent video streams, conferencing resolution supported up to 720p (1080p for Peer-to-Peer communication), H.264 SVC now default video encoding standard
Chat Room Integration with Lync Client – Merged with Lync Client (no separate client needed)
Enterprise Voice Changes
Multiple trunks between Mediation Servers and gateways, Enhanced call authorization for call forwarding and simultaneous ringing, Policy restrictions, Manager/Delegate simultaneous ringing, Voicemail escape , Caller ID manipulation, Conference dial-out for users not enabled for Enterprise Voice.
Client Side Changes from Lync Server 2010
Integration with Office Setup, Customization and Meeting Controls
•Client and the Online Meeting Add-in for Lync 2013 Preview included in Office 2013 Preview,
•Customize the organization’s meeting invitations by adding a custom logo, a support URL, legal disclaimers, etc..
•Access Chat Rooms from within Lync Client, Tabbed Conversations, Favorites for frequent contacts, Video Preview
•New attendee mute controls allow meeting organizers to mute participants
Better and Enhanced Lync Web App – Lync Web App allows PC and Mac users to join a Lync Meeting from within a web browser and now delivers a full Lync Meeting experience, including HD video, Voice over IP (VoIP), Instant messaging and Desktop, application, and PowerPoint sharing. Lync Web App plug-in is now a 7MB downloadable (from the earlier 54 MB).
Lync for mobile clients – Lync for mobile clients enables you to maintain your presence wherever you are through your Windows Phone, iPhone, iPad, or Android device.
Virtual Desktop Infrastructure Plug-in – Support for all Lync modalities, including IM, audio, video, application sharing, desktop sharing, PowerPoint sharing, whiteboard, and file transfer. Location and emergency services support as well.
Users can now mute the audience and allow or block video sharing when scheduling the meeting
Easy to use audio controls in the meeting room, content and participant views.
When sharing programs, users can select multiple programs to share
upload presentations that contain video clips by uploading the PowerPoint file.
For more:Lync Top Features