knit and gnome are similar in that both words have a silent letter/sound:
Silent letter is the letter in a word that is not pronounciated when you read it. in knit, you don't read the K sound in the beginning, and in gnome, you don't read the G sound in the beginning.
When it comes to differences:
- the obvious one of them is the meaning
- knit is a verb, whereas gnome is a noun - They are also spelled differently, because they are different words.