I think a person seeking a compassionate ear needs to be heard, validated, and help to move forward.

A self- piteous person is caught in a cycle of complaining with intent to seek pity for themselves. No action or no desire for a better outcome is not ready to hear help yet.

I think you can tell the difference because post after post you will notice small changes in attitude, tone, or perspective. These changes in reality take time and patience.

You would think ranting over and over telling the same story is helpful, I can't say for sure how many rants it takes one way or the other to get to the causation.

Both are in need of help and deserve compassion.
It is up to you to use your own discernment and how much energy to put forth.
H.