A Nova is a White Dwarf explosion less energetic than a Supernova. It is a thermonuclear explosion (CNO Cycle) of surrounding compressed Hydrogen accreted from a binary companion. Novae appear as brighter stars that gradually lose their brightness, losing 2 Magnitudes in 25 to 80 days (for faster to slower novae). Novae are regularly tracked in Andromeda as well as the Milky Way.
The term Classical Nova (CN) is sometimes used to emphasize a supernova is not what is meant. It also is sometimes used to distinguish a one-time nova from a Recurrent Nova, i.e., a star that undergoes repeated novae.
Calcium-rich Gap Transient
Cataclysmic Variable Star (CV)