there's a few user-visible changes, but for the most part they are hidden behind a setting so you won't see them unless you enable them. personally, this one is my favourite: http://imgur.com/lTncRkz
From 13.10 to 14.04 there are also an incredible amount of polish and small touches around Unity. If you aren't a consistent non-LTS user, you might miss them, but there are a lot of them and they really add to the experience.