Visit a music store or an instrument maker’s website and you will frequently see band instruments sorted into categories like “student,” “intermediate/step-up,” and “professional.” It’s important to understand that these distinctions are not bound to any specific criteria, and not policed by any governing body. The labels have a lot to do with target market, and not much to do with the instruments’ actual playing characteristics.
For example, I often have prospective college music majors proudly show me their “professional” clarinets, a specific model that a local retailer labels as such even though very few professional players would find the instrument to their liking. These students will, in most cases, have to purchase another, more expensive instrument to meet the demands of college-level playing.
On the other hand, some of my college students have instruments that are positioned by the maker as lesser than the maker’s more premium line, but which are popular and well-regarded among professional musicians.
“Student” instruments are rarely better for students, mostly just less expensive—made more cheaply or with fewer features. In most cases, if money were no object, I think it would be an advantage for a beginner to start on a high-quality (“professional”) instrument. Sometimes “student” instruments are designed to be more comfortable for smaller players, which of course doesn’t necessarily correspond to quality requirements.
Labeling instruments as “intermediate” or “step-up” is another exercise in creative writing. In my experience, these are rarely worth it—they tend to cost nearly as much as “professional” instruments but play only slightly better than “student” ones.
There are a very few other designations that have specific meanings. For example, the term “full conservatory” for oboes is widely accepted as meaning the instrument has certain required keys and mechanisms on it. However, an oboe maker or retailer can label any oboe as “full conservatory” without any formal consequence. (My nearest retailer does this exact thing.) Many makers sell “modified conservatory” oboes, which has no specific meaning—it’s just aimed at people who can’t afford “full conservatory” but like to believe they have gotten some version thereof.
If you are a student (including a college student) or are purchasing an instrument for one, you should ideally do so with significant input from your teacher. And if you are a professional, you should prioritize carefully which features and qualities are most important, regardless of labels.