As you can see from the cards above, whether an effect deals damage or just causes loss of life is dependent on the specific wording of the effect. When an effect “deals damage”, it causes loss of life (barring weird exceptions like infect), but it’s also affected by other things that affect damage; it can be prevented, for example, by something like Security Blockade, and if it’s noncombat damage, it can also be redirected from a player to a planeswalker that player controls.
Effects that state a player “loses life,” though, aren’t damage. They don’t cause damage, and they don’t get affected by anything that specifically cares about damage. Extort, for example, will bleed your opponent out right through a Security Blockade…but it also can’t be redirected to a planeswalker. Because the word “damage” doesn’t appear anywhere in the rules text of extort, it can’t be redirected, even though all the other requirements (noncombat source affecting a player) are met.
Today’s Rules Tip written by Jen Wong