One the closed buds the buds are longer and oval, on the open buds they are round and the ends are split open. Also look at the leaf cluster by the U. If the outermost leaf is leaf 1 the on the Closed bud the point of leaf 2 is left of center of the U. On the open bud the point of leaf 2 is below the right edge of the U. (This is if viewed with the you in the upright position. And I erred badly in my first post. The CLOSED bud varieties are the rare ones. I called them the common variety in my first post. Both of the two pictured are closed bud. This is an open bud:
And to add extra confusion, there is also a medium O. So you have small, medium, and large. This is a medium O open bud.