adds.cs

var findAdds =  updated
			.GroupJoin(original, l => l.Id, r => r.Id,(l, r) => new { l, r })
			.Where(x => !x.r.Any())
			.Select(x => x.l);
			
//Result:  Person { Id = 4, Name = "Jack" }

deletes.cs

var findDeletes =  original
			.GroupJoin(updated, l => l.Id, r => r.Id,(l, r) => new { l, r })
			.Where(x => !x.r.Any())
			.Select(x => x.l);
			
//Result:  Person { Id = 3, Name = "Jill" }

Lists.cs

//unmodified 
var original = new List<Person>() { 
	new Person() { Id = 1, Name = "Bryan" },  
	new Person() { Id = 2, Name = "Randy" }, 
	new Person() { Id = 3, Name = "Jill" } };

//modified 
var updated = new List<Person>() { 
	new Person() { Id = 1, Name = "Bryan" },  
	new Person() { Id = 2, Name = "Randi" }, //Update Randy to Randi	
	//Delete Jill
	new Person() { Id = 4, Name = "Jack" } }; //Add Jack

updates.cs

var updatesQuery = original
			.GroupJoin(updated, u => u.Id, o => o.Id,(left, right) => new { left, right })
			.SelectMany(gj => gj.right.Where(u => u.Name != gj.left.Name), (gj, u) => u);
			
//Result:  Person { Id = 2, Name = "Randi" }

updates2.cs

var updatesQuery2 = original
			.GroupJoin(updated, u => new { u.Id, u.Name }, o => new { o.Id, o.Name },
					(left, right) => new { left, right })
			.Where(x => !x.right.Any());
			
//Result:  Person { Id = 2, Name = "Randi" }
//         Person { Id = 3, Name = "Jill" }