The difference is a Letter of Intent is basically a letter stating the kind of offer you are contemplating in making. Usually it contains what I call the GENERAL items of price, terms and closing date. Most of the other legal STUFF is left out.
4. LOI as a Source or Promoter of Undue Litigation. Aside from the legal problem of the ambiguity and uncertainty inherent in LOI, there is yet another major problem inherent in the document, from a legal standpoint. Namely, precisely because the LOI is basically ambiguous and non_definitive by nature, the document often easily lends itself to different interpretations and understandings at the hands of different parties (or even the courts), and thus lends itself, in turn, to being a fertile source for undue litigation and legal contests for those involved with the use of that document in their transactions.