system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: The differences between acetaminophen, ibuprofen, & aspirin?

I know that aspirin helps blood clot, ibuprofen is a muscle relaxer, & acetaminophen is an NSAID. Yet all are recommended for (& provide relief for) headaches. This overlap I don't understand, what do these medicines have in common?
gpt
What's common is that they all affect the way your body creates and processes pain, but that's about it.

Why three separate ones exist is because they all have different chemical structures, and are handled when you take them by separate "metabolic pathways" (the process in which they are absorbed into, affect, and are eventually removed from the body) which make them better or worse for treating certain conditions. They all treat pain, but some are better for sprains than others (where swelling is an issue), some cause a little internal bleeding, some are better at reducing a fever, and they have different side effects. 

For example, if you have liver issues, don't take acetaminophen because it's hard on that particular organ. 

(But a correction: aspirin helps AVOID blood clots. That's why low dosage programs can help avoid heart attacks.)