I believe the Heritage '84 was just a decal package for Kirby's 75th anniversary, which put special logos on the hubcaps, bag topper, belt lifter, and handle grip, without adding any functional changes from the original Heritage. They're both model 1HD. My sense is it was just a bit of marketing, which Kirby commonly did, as with the Gsix, which got a new decal on the handle every year (e.g., Performance, 2000 Limited Edition, and 2001 Limited Edition). By contrast, the "Turbo" logo on some (most?) Heritage vacuums indicated that the unit originally shipped with a turbo brush.