Found this description of tapestry in a book I was reading and thought you might be interested:-
'Like any other woven tissue, tapestry is composed of a warp and a weft. The warp, which is nothing but a skeleton structure, disappears completely beneath the body of the fabric.All that can be seen in a finished tapestry is the weft, made up of the different coloured threads forming the decorative scheme. However the weft threads are not taken systematically across the width of the warp (as in other tissues), but only across that part of the warp corresponding to the coloured areas isolated in that section of the cartoon being woven. In other words, tapestries are woven in "patches" and several rows of the same colour are woven consecutively. By virtue of its purely manual technique and basic independence of any purely mechanical aid, tapestry fulfils all the conditions required for the production of an original work of art. It is born of the collaboration between the artist who creates the cartoon and the weaver who translates the cartoon into textile matter - not with the cold precision of a machine, but with his own personal understanding and his skill at bringing into play all the resources of his craft. This is one of the essential differences between true tapestry and the numerous other decorative fabrics produced on more or less mechanical looms which can work fast and produce less exact repetitions of the same motif."
Pierre Verlet - quoted in the book "Tapestry Weaving" by Nancy Harvey.
It seems to sum it up prretty well.