Vocations are jobs, the stuff we do (or have to do) to make money. Avocations are usually auxiliary pursuits, like hobbies or "side hustles."
So, what's the difference in the two? Perhaps it's the amount of passion we invest in the avocation that makes it less like work to us.
Consider the possibilities when our avocation is actually the same thing as (or highly aligned to) our vocation, when our gifts are not sequestered to one OR the other.
That that gets our passion gets the best part of us. And, the best part of what we have to offer.