Delphi compiler difference between IntToStr() and Integer.ToString()?

What is the basic difference between IntToStr() and Integer.ToString() when converting an Integer to a string. Which one is faster?

var
  VarInt: integer;
  VarStr: string;
begin
  VarInt := 5;
  VarStr := IntToStr(VarInt); 
  VarStr := VarInt.ToString;
end;