using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {       

        var list = new List<dynamic>();

        list.Add(new Class1(){ColumnA = "TestColumnA"});

        list.Add(new Class2(){ColumnD = "TestColumnD"});

        Console.WriteLine(list[0].ColumnA.ToString());

        Console.WriteLine(list[1].ColumnD.ToString());

        for(var i =0; i< list.Count; i++){

            Console.WriteLine(list[i].GetType().Name);          

            Console.WriteLine($"IsComponentA: {list[i] is Class1}");

        }

    }

}

public class Class1 {

    public string ColumnA {get;set;} 

    public string ColumnB {get;set;}

    public string ColumnC {get;set;}

}

public class Class2 {

    public string ColumnD {get;set;} 

    public string ColumnE {get;set;}

    public string ColumnF {get;set;}

}