Learn English – What’s the difference between “flicker” and “twinkle”

The word "drug" can have connotations of illicitness, whereas medication is always used in licit contexts. But a drug can refer to licit medicines as well. New drugs come on the market.

A drug is typically ingested (or injected) whereas medications can also be topical. Not that we don't say "topical drug" too, but "topical medication" is used more often and has been in use since the 1840s, whereas "topical drug" is a fairly recent usage, arising in the 1950s per Google ngram.

So, they're more or less interchangeable, except in illicit contexts, where drug is used. The criminal is said to be a "drug dealer", or a "drug runner", and the addict is said to be "hooked on drugs" or "on drugs". The patient is said to be "on medication".

"Cable" is thicker than "wire", however that doesn't really explain when to use each of these. Also, in American English, for household appliances or office equipment we use "cord" for some things and "cable for others", and occasionally "line" or "wire": power cord, ethernet cable, printer cable, telephone wire (or in a different context, "telephone line").

"Lead" is not common American English. I'm not sure if it's used more in Britain, or it may be used commonly in certain professions. More often in the U.S. you'll hear "wire", as in, "No wonder it doesn't work; the wire's detached."

As a related note: A recent movie "Man on a Wire" documents the amazing feat of French daredevil Philippe Petit who is (and will always be) the only man to walk between the Twin Towers of the World Trade Center in New York City. If you watch the film, obviously he uses a cable to walk on, because it's very thick and sturdy -- but he's called a "wire-walker" because that makes it sound like he's walking on something very thin and easily broken.