There is not necessarily a difference in the document per se, but it is likely a dissertation will have a broader impact and loftier goals than a thesis, simply because of the additional study, effort, and time a dissertation requires. I don't think one would be able to easily classify a document as thesis vs dissertation based on content alone. But, having the status of a 'dissertation' also suggests the author completed any number of ancillary requirements, including coursework and comprehensive/preliminary exams, which may add some weight, but that's speculative.
A journal article is something altogether different -- sometimes based on a thesis or dissertation. Journal articles must pass external peer review, whereas a thesis and dissertation is approved internally (sometimes with 1 external committee member). Also, formatting is usually dictated by the recipient journal, whereas theses and dissertation formats are dictated by the institution. It is usually the case the journal articles carry more weight than any thesis or dissertation.