Is there any difference between current IE-Appeon version and Multibrowser one regarding the supported features?

There is no difference in supported features between the current IE-only version and Cross-browsers version.

The main difference is that Appeon 2015 Multibrowser will support other browser than IE:

Apple Safari 5.1.7 or later, or
Google Chrome 35 or later, or
Microsoft Internet Explorer 6.0 SP2 or later, or
Mozilla Firefox 29 or later, or
Opera 21 or later