There are quite of lot of difference between these versions, namely invention of SAG Designer for all developments, JSON support, WS support, and enhancements, SFTP support, Service/Ehcache, Terracotta cache, UM replacing Broker, OAuth, Governance with Centrasite and Mediator, API management, Command Central and lot more to go on the list.
You can get all these differences from the release notes and readme. I suggest you have a look at them first.
#webMethods#Integration-Server-and-ESB