What is the difference between the PIC10F322 and PIC10LF322?

It is the voltage operating range. The LF is the low power version.

The PIC10F322 operates in the range of 2.3V – 5.5V
The PIC10LF322 operates in the range of 1.8V – 3.6V

Reading the datasheet, both devices can operate a full speed, 16Mhz across their voltage ranges. This is not always the case on other devices, always review the datasheet to see the respected voltage to frequency combinations.