Nihilism concludes that values have no foundation at all. Absurdism concludes that nothing warrants appeal beyond this life — and therefore that revolt, solidarity and lucid attention are the only honest responses. Camus built the second specifically by rejecting the first, which makes their common conflation a real error rather than a nuance.
Side by side
Aspect
Absurdism
Nihilism
Absurdity is in
The relation
The world
Response
Revolt, act
Withdraw — or destroy
Solidarity
Required
Unwarranted
Camus
Wrote it
Rejected it
What each one means
Absurdism
Absurdism is the philosophical and literary position that meaning is something we demand and the universe does not supply. Camus, its best-known voice, added that the right response is to keep living anyway, lucidly. Lowercase, the word can also just mean absurdity, or the absurdist strand in theatre and fiction.