This is a question I'm often asked - what is the difference? I'm all too guilty of forgetting that the differences between a tie-beam, a plate, and a girt are spatial and functional, even though they’re all beams that tie posts together.
Quite simply, all timber frames are post and beam. They rely on beams lying across posts to perform the basic structural function. However, not all post and beam buildings are timber frames. A post and beam building is a timber frame only if there is no metal in its joinery. That's another thing that is amazing about timber framing - a magnificent old barn or church is often built using wooden, furniture-like joinery, secured only with wooden pins. That's one of the reasons that engineers don't necessarily like timber frames - unlike steel structural elements, timber elements cannot always be given uniformly precise values of strength in engineering terms. Timbers are, and for hundreds of years have been, 'very strong' and unlike the modulus of breaking which can be calculated in steel or concrete to a high degree of accuracy, timbers are deemed either sufficient or not. This is changing in some of the more recent ASTM standards on timbers, but timber framed buildings rely on established precedent, knowledge about wood, and gut instinct more than math. Indeed, I have worked on barns where a huge quantity of steel was installed by engineers to reinforce the building, but it was so heavy it was actually causing the barn to collapse. Removing the steel and doing historically correct timber repairs brought the barn back to where it should be, and in the owner's words, 'it lifted back up.' There are timber framed barns that are hundreds of years old - wooden joinery is just fine for most of us, and even gives these buildings a little flex to expand, contract, and move, much more so than steel. Not better, as such, but good enough that we never have to stop doing timber joinery for substantial buildings. Thank goodness.
Posts? Yes. Beams? Yes. Timber Frame? No.