In order of seniority, the grades are...

KBE - Knight of the Order of the British Empire (Dame, DBE is the female equivalent)
CBE - Companion
OBE - Officer
MBE - Member

...and approximately the same is true of most the other orders of chivalry, such as the Order of St Michael and St George. This is the one awarded to members of the Civil Service for...well...basically for doing their job properly (which is why, I suppose, that most of them don't get it!). They are known as the Gods.....

GCMG - Knight Grand Cross of the order of St Michael and St George, aka God Calls Me God
KCMG - Knight of the order of St Michael and St George, aka Kindly Call Me God
CMG - Companion of the order of St Michael and St George, aka Call Me God

.... but I think that OMG and MMG might not exist.

Incidentally, I believe that most of the knighthoods awarded are 'Knights Bachelor' and do not admit the holder to an order of chivalry, merely to the courtesy title, "Sir".


Steve