The differences between CS1W-NC[]13 and CS1W-MC221 are as follows:

CS1W-NC[]13

Control target: Stepping Motor Drivers
Servo Motors with pulse strings
Direct Drive Motor Drivers
Control language: Ladder programming is good for simple ladder operations (direct operation or memory operation), however complex operations place a heavy load on the ladder program.
 

CS1W-MC221

Control target: Servo Drivers with analog inputs
Can connect to OMRON Servo Drivers that support absolute values.
Control language: Multitask G-language (G-language program is started from the ladder program.)
Multitask G-language allows for simple programming and is widely used for NC machine tools and position control. The load on the ladder program is light.
Others: Can be connected to a manual pulse generator (MPG).