For us the big difference is the multi-lingual Knowledge Base. That works well with users getting articles in their own languages. However, once they start raising tickets, it falls down a bit. Ticket fields, selection options, customer satisfaction surveys are all either in one language (the base language) or a mixture (i.e. a mess) with no options to change that.

In Garden I think you also get Chat and Forums. We don't use those.

There are also some smaller enhancements such as linking tickets and parent-child tickets.

Thank you Mark, much appreciated