the difference: In answer to the question about TOU; (seeing as how i own that one), it is my understanding that TOU's plays have a greater likelyhood of a higher percentage of nat gas liquids, condensates, oils, etc. And think that has been their track record at least up till now.
Whereas, PMT has been mostly nat gas; but certainly every nat gas explorer now is sucking up every drop of condensates they find.
Nonetheless, the americans sure are gloating now about their new-found shale gas reserves, and the usa becoming an exporter of liquified nat gas..