Is garam masala and chaat masala the same thing? Absolutely not. They are built for entirely different jobs, in different parts of the cooking process, for completely different flavour outcomes. One adds tang and brightness after the heat is off. The other adds warmth and depth while everything is still cooking.
Keeping both on your shelf is not a luxury — it is just basic kitchen sense. And making sure both come from a best masale company in India that puts the right ingredients in the right quantities is the part that determines whether your food actually tastes the way it should.