Exchange typically relates to money or commodities (things of value). I exchange US dollars to Euros.

Trade is usually things of similar value. We trade soccer player cards. We trade phone numbers.

Swap is usually a substitute, but can also be a very informal trade. I swap coconut oil for butter.

Sometimes they can be used interchangeably. I trade/swap shirts with my brother. There is also a formality and legality aspect to each. Exchange is the most formal and carries legal implications. Swap is the least formal with no legal protections

Good question. They are synonyms with overlapping and different uses. In general I don’t know a great way to help you learn the differences. I think things like this just take a lot of experience with a language to know which sounds natural in a given use. In the end lots of practice is the best way to learn their uses.

Exchange, I agree, is the more general word in most uses and is usually more formal too. Swap is the least used of the three, but isn’t uncommon. Trade can be best for informal uses, but can be formal as well such at world trade or a free trade agreement. Friends trade toys and such as kids, but I exchange contact information with a business contact I meet. Swap meets have products that people can swap or just for cash also. The word swap usually implies no cash involved though. People also talk about swapping roles or tasks with someone else.

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