As others have stated a walking foot moves the fabric evenly as you sew. It is really helpful when SID and putting on binding. In theory it can be used for requlat stitching but it does not work that well. I have done gentle curves and outlining with the walking foot It really seemed easier to do gental curves than using FMQ foot since yiou have more control over the movement. A FMQ foot is used to do feathers, fancy FMQ, stippling, meandering. Since it is "free" and there is no tension on the fabric and the feed dogs are usually dropped it allows the quilter to move the fabric and makes the quilting pattern "free". All that said, I use my regular sewing foot instead of the walking foot. I can sew faster and easier with my regular foot.(not 1/4" foot) also I am able to raise the presser foot tension so I have no puckering. I would suggest you get both walking and FMQ foot since each serves its own purpose.