A simple explanation, with emphasis on simple, between conformal coats and potting is:
Conformal coat is a thin, painted-on-the-board compound that protects against humidity and dust.
Potting submerges the board deeply into a substance, and protects against more harmful chemicals and provides additional mechanical protection.
As other posters have mentioned, non-acetic RTV coats cure by absorbing humidity from the atmosphere. The problem with a deep submerged conformal coat, is that the upper surface develops a "skin" that will prevent the deeper materials from completely curing.
For that reason, potting compounds are usually two-part.
Conformal coat is a thin, painted-on-the-board compound that protects against humidity and dust.
Potting submerges the board deeply into a substance, and protects against more harmful chemicals and provides additional mechanical protection.
As other posters have mentioned, non-acetic RTV coats cure by absorbing humidity from the atmosphere. The problem with a deep submerged conformal coat, is that the upper surface develops a "skin" that will prevent the deeper materials from completely curing.
For that reason, potting compounds are usually two-part.