You can have space leaks without memory leaks (if you build up big enough thunks/delayed computations/promises or otherwise run out of heap space) and you can have memory leaks without space leaks (malloc 1 byte and lose its pointer).
It's OK if you don't understand the difference yet - you'll get it eventually - but there is a big difference.
>It's OK if you don't understand the difference yet
Oh I understand the difference. But losing track of memory and accidentally keeping memory in play are both called memory leaks. I would still call it a memory leak if it's due to cyclic references or stale entries in a hash table or other container.
Yes it is. It's a description of a problem your monitoring tool has reported that needs investigation.
> Why is it not being reclaimed?
That's the first step of the investigation of the memory leak.