What is the difference between non-self and emptiness?
As I understand, Mahayana's shunyata (noun, because shunya is adjective) includes all Three Characteristics of Existence, as well as Nirvana (sometimes counted as the fourth!)

In this sense, Shunyata is the all-encompassing view, and as close as it gets to Ultimate Truth, while Anatta is but one aspect of this truth.