There is no protocol change between the versions, but it sure isn't a GUI update. Take a look at the release notes:
https://github.com/BlockchainDevelopmentCompany/Sync/releases/tag/1.1.1.0In my mind the worst part of running the older client is that it won't connect to any seed nodes without modifying the conf file. Not to mention it has a very outdated version of openssl with a lot of known vulnerabilities. More info in the link above.