As adjectives the difference between metamorphic and amorphous
is that
metamorphic is (geology) having been structurally altered as a result of, or resulting from, exposure to intense heat and/or pressure (at the contact zone between colliding plates, for example) while
amorphous is lacking a definite form or clear shape.
As a noun metamorphic
is (mineralogy) a rock that has been changed from its original form by subjection to heat and/or pressure.