O.M.G......ok the walking foot is used primary when you have a fairly think piece to sew....like a top, batting and backing and you are going to be sewing in straight lines....either stitch in an ditch or like on a diagonal or such....the walking foot has 'helpers' on the top like your feed dogs to PUSH the fabric thru...... then there is your regular foot and then there is your 'darning' foot which is usually a large circle, sometimes an open toe and when you lower it down it usually does not touch your sewing.....now when you lower your feed dogs....you can move the 'fabric sandwich' around with out touching either the bottom or the foot....that is 'Free Motion Quilting"...............
I hope that helps ....