While "toxin" refers specifically to a poison produced by a living cell or organism, "toxic" does not -- it's a synonym of poisonous, directly derived from the Latin word for "poisonous".
"Toxin" is a newer invention, derived from "toxic" by adding the biochemistry-related suffix "-in" to indicate toxic substances of biological origin.
"Toxin" is a newer invention, derived from "toxic" by adding the biochemistry-related suffix "-in" to indicate toxic substances of biological origin.