What are delusions and delirium?

Neuropsychiatry. Delusion: is a false belief that is maintained even though it is contradicted by reasoning. It is a psychiatric disorder. For example if i think I am george washington or that i talk to god, that I am a special mesenger from god all these are delusions. Delirium is acute brain syndrome produced by disease during which patients are confused, hallucinate, and have global impairment of thinking;.
Symptom vs syndrome. Delusions are fixed false beliefs for example that someone is trying to kill you. Delusions can be seen in many different illnesses including delirium. Delirium is a medical condition that evolves fairly quickly involving trouble with attention, vital sign fluctuations, confusion and even hallucinations. Finding the cauuse and treating the person are very important.