A ditch foot rides in the seam and is helpful for stitching-in-the-ditch. That is the only quilting task it is useful for, as far as I know. You cannot use it to sew on bindings, for example, which is one of the uses for a walking foot. You can also use a walking foot to quilt straight lines, or end-to-end wavy lines (talk about easy quilting!). If you can afford only one or the other, I would get the walking foot.