The measurement of draw length is often different between recurve and longbow, because you measure it at the far side of the shelf (the back of the bow). Recurves often have thicker risers, from back to belly, and draw length will measure longer on a recurve. This is the case with Black Widows, and I shoot recurve and longbow. My measured draw length is somewhere around 1/2" shorter with the longbow than with the recurve.
If, for each bow, you measure the distance from the deepest part of the grip to the shelf at the back of the bow, the variation between the two bows would be a significant part of the difference between measured draw lengths between the two bows.