Classicism is the designation for art that draws inspiration from the styles of ancient Greece and Rome.
Classicism, in its broadest sense, refers to the artistic style that imitates the classical art of ancient Rome and Greece. It has its roots in ancient times but has had various revivals in history, especially during the Renaissance and the Age of Enlightenment.
Neoclassicism, on the other hand, specifically denotes a period in the late 18th to early 19th century when artists worldwide aimed to rekindle the classical style of Roman and Greek art. It was a distinct era within the broader continuum of classicism.
In summary, classicism has been a recurring artistic style, with neoclassicism being one of its notable revivals, particularly in the late 18th and early 19th centuries.