They started as same word, but their meanings have drifted apart over time.
A word that (literally) drives people nuts
Often used, often confused. Here's some guidance and insight.
Comedian ISMO on the complexities of the word 'tip'
Some practical guidance, and interesting history, about a common mistake.
Why does it sound strange to say 'funner' or 'funnest?'
English was never the same after the Norman Conquest