Difference between await & GetAwaiter()/GetResult()

if (!_roleManager.RoleExistsAsync(SD.Role_Customer).GetAwaiter().GetResult())
  {
    _roleManager.CreateAsync(new IdentityRole(SD.Role_User)).GetAwaiter().GetResult();
    _roleManager.CreateAsync(new IdentityRole(SD.Role_Moderator)).GetAwaiter().GetResult();
    _roleManager.CreateAsync(new IdentityRole(SD.Role_Admin)).GetAwaiter().GetResult();
    _roleManager.CreateAsync(new IdentityRole(SD.Role_Invited)).GetAwaiter().GetResult();
  }

if (!await _roleManager.RoleExistsAsync(SD.Role_Customer).GetAwaiter().GetResult())
  {
    await _roleManager.CreateAsync(new IdentityRole(SD.Role_User));
    await _roleManager.CreateAsync(new IdentityRole(SD.Role_Moderator));
    await _roleManager.CreateAsync(new IdentityRole(SD.Role_Admin));
    await _roleManager.CreateAsync(new IdentityRole(SD.Role_Invited));
  }