Just looked at the manual for the C11, and it has jumpers to select pull up, or pull down resistor for each input.
Without going into too much detail, the NPN/PNP refers to the type of transistor used to switch the sensor output. A NPN transistor will switch to earth, where as a PNP transistor will switch to supply voltage.
In this application, using an NPN, the input pin must be pulled high, and will then be driven low when the sensor is activated. A PNP requires the input pulled low, and will then drive it high when activated.
The benefit of the C3, is it provides a TTL output, which doesn't require the use of any external pull-up resistors. The TTL actually drives the output high or low, instead of leaving it to 'float' when not activated. This is what the original C3 would do if set to Open Collector mode.