Single-pole switches the Live
Double-pole switches the Live and Neutral

The use of double-pole switching guards against the dangers associated with a Live/Neutral reversal. A single-pole switch breaks the circuit on the Live; however, the possibility of electrocution exists if the Live and Neutral are wired the wrong way around.

In summary, so long as everything is wired correctly, single-pole switches will suffice, but to guard against a Live/Neutral reversal, double-pole switching will always ensure safe disconnection.

Glossary term link: Single and Double Pole