El trabajo y los estudios

Papel is paper. It is also the role you play, in a film or in a team: hacer un papel is to play a part. English borrowed the same metaphor from French and then forgot it, so the connection reads as odd to us and as completely unremarkable in Spanish.

profesor and maestro

Both teach, and in Spain they are not interchangeable.

Maestro is a primary school teacher, and by extension a master of a craft: a maestro in the kitchen, a maestro on the guitar. It carries warmth and a little deference.

Profesor teaches secondary school or university. It is the neutral, slightly formal word, and it is what you call the person standing at the front of a language class.

In Spain, call a university lecturer maestro and you have said something odd but affectionate; call a primary teacher profesor and you have merely been stiff. In Mexico maestro is the everyday word for any teacher, university included.

trabajo does the work of three English words

Trabajo is work as an activity, work as a job, and a piece of work you hand in. Busco trabajo is I am looking for a job. Tengo mucho trabajo is I have a lot on. Un trabajo sobre Cervantes is an essay.

The verb trabajar is regular and behaves itself, which after ser, ir and tener feels like a gift.

Compañía and compañero

Compañía is a company in the business sense, and also company in the sense of being accompanied. Compañero is the person you share it with: a classmate, a workmate, a partner. It is one of the most useful words on this list and English has nothing that covers the same ground without sounding either corporate or romantic.

estudio

Estudio is study, a studio, and the first person of estudiar. Spanish is untroubled by this. Estudio en la universidad and un estudio de grabación sit side by side and nobody has ever been confused by them, which is a useful reminder that ambiguity in the abstract is rarely ambiguity in practice.