It is worth mentioning that Single Pole & Dual Pole devices are switched via Toggle Operation only and Three Pole/Four Pole can be either switched via Toggle Operation or Rotary Handle. If Rotary Handles are required then a 4 Pole or TP&N can be cabled up as a single/two pole and used as such requirements.

Obviously, it depends on the application to what is required, the main question is, should you have a switched neutral?

On Single Pole & Neutral & Three Pole & Neutral systems the neutral is continuous throughout the entire system, the choice between this typically comes down to your earthing systems, and therefore when all the current carrying lines (including the neutral) need to be switched, typically in a TN-S System