Professional meaning: it is the major you chose when you were admitted. The major that was admitted. Or your major after college. This is your major. After graduation, the corresponding degrees and diplomas will be awarded. These two certificates are recognized by the state.

Minor means: it is another major you choose after you go to college. Only certificates recognized by the school will be issued after graduation. It is still useful to find a job.

A double degree is to learn a major well before applying for another major, so that you can get two professional degree certificates when you graduate.

Elective meaning: it means that the courses offered by the school to all students are optional. If you just want to learn, not to get credits, just listen as long as others teach you, and nobody cares.

Make sentences:

I majored in interior design at the university.

When I went to work, I found that I was not good at plane, so I found a training institution to minor in it.

During my college years, I studied animation and interior design, and I chose two majors.

Drawing, dancing and playing the piano, I chose a dance I like.