PSI (pounds per square inch) is a unit of pressure that is commonly used in the United States. It is defined as the force of one pound acting on a surface area of one square inch.

Pascals (Pa) is the unit of pressure in the International System of Units (SI). It is defined as one newton per square meter.

1 PSI is equal to 6,894.757 Pascals.

Here is a table summarizing the key differences between PSI and Pascals:

| Feature | PSI | Pascals |

|---|---|---|

| Unit of measurement | Pounds per square inch | Newtons per square meter |

| Common usage | United States | International System of Units (SI) |

| Conversion factor | 1 PSI = 6,894.757 Pascals | 1 Pascal = 0.000145 PSI |

In general, PSI is used to measure pressure in smaller systems, such as car tires or air compressors, while Pascals are used to measure pressure in larger systems, such as water pipes or hydraulic systems.