difference between unit/integration test and component/functional test

I'm java dev and understand unit test and integration test well, but at this place they used Jbehave framework and divides the tests to component and functional tests, which confused me. my questions are:

1. is it true that unit and integration tests are whitebox testing while component and functional tests are blackbox testing?

2. I read some internet post about functional test, it's high level test for system like web app + backend api service, but our system is a pure backend service, we push data to event hub, then run the server which pull data out of event hub and push to database. I just don't see what kind of functional tests i can create for this. it's exactly an integration test + some BDD story description.

3. For real BDD, shouldn't the PO/PM or BA create the scenario/stories then dev develop the test codes? here we as developers do both, so feel really like writing integration tests plus some extra words

anyone can explain this?