The neck yoke is the "traditional" ox yoke of the United States. As the name suggests the yoke rests on the oxen's neck. The beam is held in place by the oxbows.
Head yokes are secured to the oxen's horns and/or forhead; that lashing transfers the power from the oxen to the yoke, which in turn transfers the power to the work. Headyokes must be carefully fitted to the individual ox.
The ox collar does not quite fit the definition of an ox yoke, but it is yet another way to transfer power from the ox to the work at hand. See also: A Horse Collar Doth Not an Ox Collar Make