I'd never found sucha great explenation. Enjoy it!
What's the Difference Between Engraving and Thermography?
ngraving and thermography are actually quite different from one another but these two printing methods are frequently confused. The printing results can be somewhat similar and can commonly be found on wedding invitations, business cards and the occasional letterhead.
Engraving is a kind of gravure printing wherein paper is pushed against a recessed plate. In engraving, the paper is usually slightly moist. The pressure of another cylinder forces the ink from the recessed area onto the paper. The pressure of the press raises the imprinted area slightly which gives the piece what we recognized as an engraved appearance.
Thermography, also known as the "poor man's engraving" method, is somewhat similar to engraving in result but not process. It's cheaper and easier to produce than traditional engraving which may account in part for it's popularity. Thermography is created by adding a powder to the ink being printed on a paper's surface. The printed piece is then passed under heat and literally cooked together. When heated (it's thermography after all), the ink and powder blend and rise to give a raised effect. Frequently thermography appears even more engraved than some engraved printing.