This is a critical distinction for learners. While both can be translated as “cherish,” they have different focuses.
`爱惜 (àixī)` focuses on the action of careful use to prevent damage, waste, or wear. It's about preservation through action. It's often used for things you can “use up,” like objects, health, and resources.
`珍惜 (zhēnxī)` focuses on the internal emotion of valuing something and not taking it for granted. It's about appreciating the value of something, especially things that are abstract, fleeting, or irreplaceable like time, relationships, memories, or opportunities.
Rule of Thumb: If you can physically “use it carefully,” lean towards 爱惜. If you are appreciating something you can't “use” (like a friendship or a memory), lean towards 珍惜. For “time” (时间), both are possible, but with a slight difference: 爱惜时间 (don't waste time) vs. 珍惜时间 (value the time you have).