Enamel cloisonné
Twisted wires are soldered to the surface in a certain pattern to build small cells which were filled with translucent enamel in different colurs and shades.

Enamel cloisonné with enamel painting
The same as before only certain spaces were also painted with enamel (not translucent)

Enamel champlevé
The surface is in a certain pattern engraved and filed with enamel (not translucent)

Enamel champlevé with enamel painting
The same as before only certain spaces were painted with enamel (not translucent)

Enamel painting
The object or parts were painted with enamel

Enamel plique-a-jour
The most difficult technique!
an object get a transparent pattern (holes etc. in the surface), which was later filled with transparent enamel - churchwindow optic.

Regards
Postnikov