What is the difference between an Emir and a Sultan? Are they both Sheik?
For instance, OALD defines:
Emir: the title given to some Muslim rulers
Emirate: an area of land that is ruled over by an emir
Sultan: the title given to Muslim rulers in some countries
Sultanate: an area of land that is ruled over by a sultan
While OAAD defines (there is no entry for Sheik on OALD, why?):
1 an Arab prince or leader; the head of an Arab family, town, etc. / 2 a leader in a Muslim community or organization
Could we say that "Emperor":"King"="Emir":"Sultan"?