Silent is a marketing word rather than a specification, and no compressor with a motor in it is actually silent. What the description usually signals is a quieter piston design, and more importantly a tank, because a compressor with a tank spends most of its time switched off. If you paint in a flat, in the evening, or anywhere near someone else, that difference matters more than any other feature.
What quiet actually means here
A tankless compressor runs continuously for as long as you are spraying, so the noise is constant. A compressor with a tank fills the tank, stops, and only restarts when the pressure drops, so the room is quiet for most of a session and noisy in short bursts. That is the change people describe when they call a compressor silent. There are genuinely quieter motor designs as well, and they cost more, but the tank is the feature that transforms the experience and it happens to bring several other benefits with it.
Everything else a tank improves
Stored air is steadier than air straight from a piston, which shows up as smoother coverage and less spatter at low pressure. A motor that runs a fraction of the time runs cooler and lasts longer. Air that sits in a tank cools, which drops some of its moisture in the tank rather than in your paint. None of these is the reason people buy a tank and all of them are reasons to be glad they did. The costs are size, weight and price, which is a real trade for anyone short of desk space.
Propellant cans, and why they disappoint
A can of airbrush propellant will drive an airbrush and needs no power, which makes it tempting for occasional use or for someone testing whether they like the tool. The problems appear quickly: pressure falls as the can empties, so the spray changes during a session; the can gets cold in use, which drops the pressure further; and the running cost is high compared with a compressor that lasts years. As a way to try an airbrush once it is defensible. As an air supply it is the least satisfactory option available.
Questions people ask about silent airbrush compressor
Are silent airbrush compressors really silent?
No. The term usually means a quieter design and, more importantly, a tank, so the motor is off for most of a session rather than running continuously.
Is a compressor with a tank worth it?
For anyone painting regularly, yes. It gives steadier pressure, a quieter room, a cooler motor and drops some moisture in the tank rather than in your paint.
Can I use airbrush propellant instead of a compressor?
For an occasional session, yes. Pressure falls as the can empties and the can chills in use, so the spray changes as you work, and the running cost is high.