In France the pronunciation is exactly the same : [sa]. But the context will always give you a hint about which one is used.

En France, la prononciation est exactement la même : [sa]. C’est le contexte qui permettra de déterminer lequel des deux est utilisé.

The other answer is valid only for European French.

In Quebec, the pronunciation of ça in stressed position (as in “Je veux ça”) is [sɑ], but [sa] in unstressed position (e.g., “Ça va”, [sa vɑ].) However, sa is always [sa], even if it is stressed: “C’est sa brosse [i.e., à elle] que je veux.”

Well, yes they sound same. But I would say that depends on where you find it in the sentence. At the end, like when to show something, the pronunciation could be frank. The sound is cutt, (like →).

But at the beginning of a sentence it could finish lower (like ↘).
In other terms it could be compared to a sinus or square form ending.

For these words that’s not so important but this is a good approach for French and all latin languages I think.

In fact, starting with a strong “Ça”, like you can say “ça” to show something in a sentence’s ending, could be interpreted as intransigent/non-polite. Because the “square sinus” has been used.

The “sa” stay mostly neutral, but owns somes variations only in familiar/street speaking. Because it’s feminine, and because it’s possessive, it can be used as a punctuation in sentence, a rolling-over or a point of turning in sentence. On this case you can hold the “s” a bit longer and even only on this case finish ↗ with no mouth cut.