As the name suggests the collar without flap is composed only of the collar stand. It can vary by its height, its shape (rounded, square or bisected) and especially by its buttoning. There are, therefore, two types of collars without flaps: the officer collar (or grandfather's collar) and the mao collar.
First, the officer collar (or grandfather). Its name comes from the collars bordering the neck of the officers' jackets. The ends of the collar meet and intersect allowing a closure with a button. This type of collar is rather casual and is rarely worn tie.
Then the Mao or Mandarin collar. Of Chinese origin, the latter may have jointed or spaced ends, but it differs from the official collar by the fact that these ends do not intersect and therefore this collar does not close. More original and a little less casual, it can be worn with a bow tie or an ascote.
Mao collar on oxford shirt
officer collar col officier with white piping for nightgown