Both Ki and Positive Energy have been described as a "life energy" or "energy that flows through all living things"

So are they the same? What is the essence of "life energy?"

Aaaand do all creatures have the same amount of it?

Edit: I am the DM asking for other's input

Those are very excellent questions for your DM. If you are the DM, then the answer is it works however you think it should for your world.

Quote from SweenyTodd>>

Both Ki and Positive Energy have been described as a "life energy" or "energy that flows through all living things"

So are they the same? What is the essence of "life energy?"

Aaaand do all creatures have the same amount of it?

 That is probably a no. No matter how you measure, larger or more supernatural creatures should have more.

Quote from Kotath >>

Quote from SweenyTodd >>

Both Ki and Positive Energy have been described as a "life energy" or "energy that flows through all living things"

So are they the same? What is the essence of "life energy?"

Aaaand do all creatures have the same amount of it?

 

Well all creatures clearly do not have equal amounts of Ki. This is evident in the fact that, for monks, it or at least access to it is based on level. Traditionally, it varies with individual.

They don't, but the monk Ki system is about being able to use your life energy, not the amount of it you have.