What is the difference between WL01CA2 Limit Switches and the WLCA2?

The "01" in WL01CA2 means that it is for microloads. 

Microload Models (Refer to the following information when using the WL01CA2.)

Rated voltage (V) Resistive load (A)
125 VAC 0.1

It is best to used the WL01CA2 in the range shown in the following figure.

Recommended load range 5 to 30VDC
0.5 to 100 mA