I see difference between the jewel worn by the Countess of Strathmore for the 1937 Coronation and the Teck circles tiara.
It seems to me that, in the upper portion of the jewel worn by the Countess, the individual elements have a more elliptical shape than the crescents in the Teck tiara, and that those elements do not have an open section on one side.
Other differences are -
1. In the tiara worn by the Countess there are small upright elements separating the elliptical elements.
2. There is no sign of the three rose elements so prominent in the Teck crescent tiara in the jewel worn by the Countess of Strathmore.