In physics|lang=en terms the difference between semiclassical and semiquantum

is that semiclassical is (physics) describing any of various approximations to either relativistic or quantum mechanical physics that retains elements of classical physics while semiquantum is (physics) describing any system that shows some characteristics of a quantum one; semiclassical.

As adjectives the difference between semiclassical and semiquantum

is that semiclassical is (music) describing classical music of broad, popular appeal while semiquantum is (physics) describing any system that shows some characteristics of a quantum one; semiclassical.