What is new in InfoPath 2013 compared to InfoPath 2010 ?

There is just a minor change in the look and feel of  the InfoPath 2013 forms from InfoPath 2010 .

Please find the details at http://msdn.microsoft.com/en-us/library/office/jj229830(v=office.15).aspx#odc_off15_ta_WhatsNewforO15Developers_InfoPath

There are few more links which talks about the minor change from InfoPath 2013 from InfoPath 2010

http://infopathtips.com/2012/10/28/whats-new-in-infopath-2013/

http://www.projectpoint.at/?p=925