They started as same word, but their meanings have drifted apart over time.
Comedian ISMO tries to figure out 'one' and 'two'
You all would not have guessed some of these
Is it all the same anyway?
Why don't they call it the Merriam-Webster comma?
And who put it there, anyway?
You don't have to end all your adverbs in -ly to talk right.