pressure 與 stress 的分別?

You could find a description on the difference between" pressure" and "stress" in the following article:

http://www.geol.umd.edu/~candela/press.html

Although the aricle is on the applicability of "stress" and "pressure" in geology, the interpretation could be equally applied to physics application. Basically, when considering the forces that act insie deforming materials, the ratio of the internal force that distributed over the surface of an element of the material to the area is termed "stress".

The term "pressure" is used when the stress-field is hydrostatic.