Get value from Generic List

HI,

I have two lists are tab1 and tab2 with same properties are called ABUId,User,BuildingId,UserFolio and BuildingName.

Here I need to get data which available in tab1 and which not available in tab2.here Consider only BuildingId and User data.

please refer below source code..

Note:- One BuildingId can mapped with multiple user.So combine these both things and need to select correct one which is in tab1 and if that not in tab2.

var tab1 = listBank;

var tab2 = DataTable1.AsEnumerable().Select(dr => new Bank { ABUId = "0", User = dr.Field<String>("User"), BuildingId = dr.Field<String>("BuildingId"), UserFolio = dr.Field<String>("UserFolio"), BuildingName = dr.Field<String>("BuildingName") }).ToList();

//Here I need to select which is available in tab1 and if that not available in tab2
var NeedToDelete = ?

var finalRec = NeedToDelete.Where(x => !x.User.Equals("JOHN", StringComparison.InvariantCultureIgnoreCase)).Select(x => x).ToList();

if (finalRec != null)

{
    foreach (Bank bank in finalRec)

    {
       //For my Further calculations
        
    }
}

Thanks in Advance..!