Below are two photos of two 4W-W’s. On top is “Santa Claus’ below is ‘Rose of May’. I find ‘Rose of May’ more rounded in the petals and less formal than the much admired ‘Santa Claus’. The petals on ‘Santa Claus’ are more pointed and arranged with far more symmetry.
‘Rose of May’ is “in the bulb trade” and available in the mass market occasionally. ‘Santa Claus’ is much more difficult to find. Both were introduced the same year (in 1950) by Guy L. Wilson and are siblings from the same cross. To me, here in my climate, I find ‘Santa Claus’ to be the best show flower but a slower increaser. Both are extremely late with ‘Santa Claus’ a few days later than ‘Rose of May’.
Steve
PS – Sorry for the slug damage on the ‘Rose of May’ photo.
Steve Vinisky 
Sherwood, Oregon USA Located 25 miles SW of Portland. (The sign here says “Welcome to Sherwood” on both sides)