As nouns the difference between psychedelic and ergoline

is that psychedelic is any psychoactive substance (such as lsd or psilocybin) which, when consumed]], causes [[perception|perceptual changes (sometimes erratic and uncontrollable), visual hallucination, and altered awareness of the body and mind while ergoline is (chemistry) a tetracyclic heterocycle whose structural skeleton is contained in a diverse range of alkaloids, including some psychedelic drugs, and whose derivatives are used clinically for vasoconstriction and in the treatment of migraine and parkinson's disease.

As an adjective psychedelic

is of, containing, generating, or reminiscent of drug-induced hallucinations, distortions of perception, altered awareness etc.

As an interjection psychedelic

is awesome, cool, groovy.