system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is the difference between acetaminophen, ibuprofen, and NSAID?
gpt
NSAIDs are a class of drugs that reduce your body's response to things like inflammation, injury and distress, which reduces the pain associated with conditions like fevers or muscle soreness.  Ibuprofen is one of the medicines in this class, so there's no difference there.

Acetaminophen is not an NSAID.  While it does act to reduce fever and pain (which it has in common with NSAIDs like ibuprofen), it does not affect inflammation, so it is not an NSAID.  NSAID stands for Non-Steroidal Anti-Inflammatory Drug.

Drugs are processed, used and excreted by different organs.  Because acetaminophen is mainly processed for excretion by your liver, it is not recommended that it be taken by drinkers, because alcohol is also processed by the liver.  Too much stress on the liver damages it.

Ibuprofen is processed more by the pancreas, so it is considered safer to use by those than drink alcohol.  

All of these drugs share a molecular structure that can irritate the stomach, so taking any of these drugs is best with a full glass of water.  If stomach upset occurs, you should consult a physician.