Why do Assert.IsTrue(Equal) and Assert.AreEqual return diferent results

I orginally has a UNIT test saying this

Assert.AreEqual(blank, edit.Core);

because the assert was failing i swapped it with this to help me step through and diagnose the issue

var comparer = EqualityComparer<T>.Default;
bool tmp = comparer.Equals(blank,edit.Core);
Assert.IsTrue(tmp);

however i no longer have an issue. so why does Equal A, b return true and assert areequal fail?