There's not much difference but what you're saying is basically true. In forex, you will be studying and monitoring those steps taken by countries that may affect the value of their currency. In crypto trading, you will be studying and monitoring the specific crypto. In forex, you will have to watch the global market as well. In crypto, you will closely watch the entire crypto market also.
Here's the big difference: in crypto, you will easily gain a huge profit. In forex, it would be harder. In crypto, alts double, triple, quadruple, etc their value in a short time. In forex, it simply won't happen.
I was once interested also in forex trading, and i never had the courage to try it because i have heard so many issues and also one of my friend told me not to try without saying a word or his reason why even if i ask him why. Just like OP i am also wondering why and how they earn from forex.
