system
Given the following post, respond as if you're commenting on Reddit:
human
eli5: What makes electrical motors in cars so quiet?

I mean in comparison with other motors, like power tools or even home appliances? Is it just sound insulation or is it a different kind of motor?
gpt
Many power tools, kitchen appliances and vacuum cleaners use universal motors, because they're cheap and power dense, but they're also very mechanically noisy. There's also in many cases cheaply made gearing that's noisy as well. Universal motors have brushes and are not very long-lived, so EVs use long-life brushless motors that are much quieter, and helical gears that cost more but are quiet and wear-resistant.