Collotype printing and Heliotype

Collotype printing noun - A photomechanical printing process that uses a glass plate with a gelatin surface that carries the image to be reproduced; can be used with one or more colors.

Heliotype and collotype printing are semantically related. In some cases you can replace term "Heliotype" with "Collotype printing", this terms are similar.

Heliotype noun - Duplicator consisting of a gelatin plate from which ink can be taken to make a copy.

Collotype printing and heliotype are semantically related. You can use "Collotype printing" instead a noun "Heliotype".