Set Apart Meaning

Example: To select (something or someone) for a specific purpose.
To distinguish, make obvious the distinction between (two things) or of (something).
2013 September 28, Kenan Malik, "London Is Special, but Not That Special," New York Times (retrieved 28 September 2013):
  It is one of the ironies of capital cities that each acts as a symbol of its nation, and yet few are even remotely representative of it. London has always set itself apart from the rest of Britain — but political, economic and social trends are conspiring to drive that wedge deeper.
Used other than as an idiom: to separate or isolate.