Differences between atmospheric pressure and liquid pressure

The difference is that liquids are nearly incompressible.

Explanation:

if we compare air-pressure (atmospheric) and liquid-pressure (fluid), then the difference is that liquids are nearly incompressible, and conforms to the shape of its container but retains a nearly constant volume independent of pressure. — while air is a compressible fluid — its density changes with pressure

(https://www.quora.com/What-is-the-difference-between-atmospheric-pressure-and-fluid-pressure)