Interesting, thanks for sharing. Based on your comment I looked it up and found 6 other orders, including Order of Saint Michael and George that you mentioned. OBE is apparently not the most prestigious one, the highest and most prestigious one is apparently called The Most Noble Order of the Garter. Interesting slice of old royal UK culture.
Yes. The Garter and the Thistle (and the Order of Merit) are exclusively small and also in the personal gift of the sovereign. The Order of the British Empire is much larger and appointments are made on advice from the government.