It's suggested to use LINQPad 5 (download link: http://www.linqpad.net/download.aspx). See what's the difference between lambda delegate and lambda expression tree.

TreeVsDelegate.linq

Func<int, int, int> addDel = (a, b) => a + b;
Console.WriteLine(addDel);

int d = addDel(1, 2);
Console.WriteLine(d);


Expression<Func<int, int, int>> addExp = (a, b) => a + b;
Console.WriteLine(addExp);

addExp(1,2);

Func<int, int, int> addCompiled = addExp.Compile();
Console.WriteLine(addCompiled);

int c = addCompiled(1, 2);
Console.WriteLine(c);