Both the Housewife and Oxford Edge pillowcases fit snugly around the pillow, but the Oxford has a wide stitched flat hem round the outside to create a border. The Oxford Edge looks bigger, but the internal dimensions for the pillow are the same.
Housewife or Oxford does not mean they are standard size, you can have square Housewife pillowcases, square Oxford edge pillowcases, King Size Housewife pillowcases, etc. Housewife or Oxford just basically means that they have no border (Housewife) or they have a border (Oxford).
This applies to all sizes of pillowcases and also to the duvet covers, you can have Housewife duvet covers or Oxford Edge duvet covers.