Clifton explained the differences pretty well. As far as what is better for which, it, like Clifton says depends on a lot on personal preference but I think most would lean towards the touring bike for commuting.

It depends on whether or not you want to carry much on the bike and the condition of the roads. If you use a backpack or messenger bag and ride on good roads, the advantages of the touring bike start to matter less.

For a century again I think it depends. There's a lot of road bikes which aren't touring bikes but not all out racing bikes either. They have slacker angles for a more stable ride but maybe not as long as chain stays or the canti-brakes of a touring bike. These would be great for an unloaded Century.