They started as same word, but their meanings have drifted apart over time.
Figuring it out at once
'Poets laureate'? 'Court-martials'? The curious history of postpositive adjectives in English.
Comedian ISMO on what separates a boot from a trunk
Why both words are equally good for you.
How 'literally' can mean "figuratively"
A simple way to keep them apart. (Most of the time.)