DEFINITIONS:
Basse-taille (bahs TIE yuh) (low cut) and Guilloché (gee oh SHAY) (engine turned) enameling are engraved metal covered with translucent enamel that allows the pattern to show through. The difference is in the way the engraving is done. Basse taille work is engraved by hand while guilloché work is machine-engraved using an engine-turning lathe, or tour a guilloche. Professional Jeweler Magazine Archives

Champlevé (chaw le VAY) (raised field) powdered glass is placed in areas of a piece of jewelry that have been carved away specifically for this purpose before firing. The glass powder melts filling the carved areas with solid glass.Champlevé is similar to cloisonné, but not as delicate.

Cloisonné (klwah son NAY) (partitioned off/cell) a method of applying enamel to metal in which the design is first outlined on the metal surface using a metal wire. The space between the wires is filled with enamel and then fired to a glassy sheen.

Grisaille (gri-zA) (greyness) enamel in a monochrome that uses mostly colors of white with gray and/or black.

Limoges [lee MOZH] (enamel) Enameling technique: painted enamel applied one color at a time, fired after every application, producing a picture-like image, named after a town in France where the technique originated.

Plique à jour (pleek ah ZHOOR) (light of day) . Enameling technique in which the groundplate is removed after firing, the translucent enamel then resembling stained glass.The style was most popular during the Art Nouveau era. It's some of the most beautiful type of enamel jewelry.

Taille d’épargne (tie yuh day PARN) (saving, economical cut) . Enamel technique: engraved design partially filled with opaque enamel, usually black.

Definitions courtesy of following sites:

Center4jewelrystudies.org