What is the difference between 'While' and 'When' abilities in Riftbound, and can opponents react to 'While' abilities?

Ruling: 'While' abilities are passive abilities that don't use the chain and cannot be reacted to as long as their condition is fulfilled. 'When' abilities are triggered abilities that use the chain and can be reacted to.

Nuances:

• Passive abilities are always true when their condition is met, without using the chain
• In the example given, an opponent cannot play a reaction spell to kill Wielder of Water before its 'While' passive resolves, since passive abilities don't use the chain