В чем разница между I lost my AirPods that was given to me for my birthday. и I lost my AirPods which was given to me for my birthday. ?Пожалуйста, приведите примеры.

Usually you use “that” when there are more than one of the thing you’re describing:

If I say:
“This is my skateboard that got broken.”
It means that you have more than one skateboard but you are only talking about the broken one.

You use “which” to describe the object and it gives no other information about whether you have more of that object or not.

If I say:
“This is my skateboard which is broken.”
You know that the skateboard is broken, but you don’t know if I have more skateboards or if the broken one is the only skateboard I own.


//TLDR:
I would use “that” here even though you may not have other AirPods.

-> I lost the AirPods that were given to me for my birthday.