What makes "Probability" different from "Possibility"?

If something is possible then it can happen according to the laws which govern our universe. If something is probable then it first has to be possible, and also has to have a non-minute chance of happening. So someone might say that flipping a coin and it landing on it's edge is impossible because we assume that head and tails each have a 1/2 chance of occurring, thus making the probability of it landing on it's edge zero. But this is not the case. An edge landing is possible, it's just not probable. The probability of that event isn't zero, but it's so low that it's essentially zero; i.e. you wouldn't expect it on any given coin toss.

"Possibility" is an English term

describing whether or not something can occur in reality.

"Probability" is a Mathematical term

describing the likelihood of something occurring.

One can say that the probability of something being zero is the same as "impossible";

but one can't say that something which is "impossible" has a probability of "zero".

- Likelihood (in reality) implies (possible) existence.

If an event is possible then the probability of the event occurring is greater than 0. The term "probable" is more subjective but it could mean that an event is more likely to happen than to not happen (eg the probability is greater than 0.5).

Then again you could be referring to the more probable event. If you have 3 events with probability 0.4, 0.35 and 0.25 then the event with 0.4 probability is more likely to happen than either of the others, but is it the probable result?

Technically speaking, there is a subtle distinction between probability = 0 and "impossible" but they are essentially the same thing.

possibility is a term used in english.

But, probability is a mathematical term.

It's just like saying 'curve' instead of parabola.