My understanding is that “persons” refers to people in discrete groups, where what separates those groups is pertinent to the topic being discussed.

For example - ‘indigenous persons’ refers collectively to indigenous people, but acknowledges that there are separate subgroups of indigenous people within that. You could equally say “indigenous people” and it would be correct but you lose that nuance by not acknowledging that there are internal divisions within the group you are referring to.

Not saying that’s the dictionary definition, but that’s how it’s generally used in my field.