Deposition is to deposit something, say a coating onto a metal. Precipitation is like a shower of rain, fime liquid spray falling onto something. DIsclaimer...I am not a chemistry expert, but I did science at school and my father was a Chemical englineer, so I am only answering as an amateur, and only in case no one else can answer, hoping it helps.

Hi Zoe! That's a good question! I work in a genetics lab and this is how I would use the different words. Precipitate: You can precipitate DNA out of solution (in other words I've actively done something in an experiment to make something fall out of solution and it should fall out quickly) Deposit: There's some sort of deposit that the water left on my sink, the water must have a lot of calcium in it (in other words I would generally use deposit to describe a naturally occurring reaction that takes a longer time to see) Here's a good resource that may help: https://wikidiff.com/precipitate/deposit