Mycontext mycontext = new Mycontext();
var list1 = mycontext.ExampleAs.ToList();
var list2 = mycontext.ExampleBs.ToList();


var notcontainId=list1.Select(l1 => l1.CreatorId).Except(list2.Select(l2 => l2.Id)).ToList();


List<Result> results = new List<Result>();
var result1 = (from a in mycontext.ExampleAs
              from b in mycontext.ExampleBs
              where a.CreatorId == b.Id
              select new Result
              {
                  Id = a.Id,
                  Name = b.Name
              }).ToList();
var result2 = (from a in notcontainId
               from b in mycontext.ExampleAs
               where a == b.CreatorId
               select new Result
               {
                   Id = a,
                   Name = null
               }).ToList();

results.AddRange(result1);
results.AddRange(result2);
Console.WriteLine();



public class Result
{
    public int Id { get; set; }
    public string? Name { get; set; }
}