Alumno vs. estudiante
Though alumno and estudiante both translate to student or pupil in English, their usage and connotations in the Spanish language can be slightly different. Both words are used to describe individuals who are learning or studying, however, the context and type of relationship they imply can vary.
Alumno
A2Alumno is commonly used to refer to someone who is enrolled in a school or a particular course/class. This term emphasizes the relationship between the student and their teacher or educational institution.
Soy alumno de la Universidad de Salamanca.
(I'm a student at the University of Salamanca.)
Los alumnos deben entregar los trabajos antes del viernes.
(The students must submit the assignments before Friday.)
El profesor felicitó al alumno por su excelente trabajo.
(The teacher congratulated the pupil for their excellent work.)
Estudiante
A1Estudiante simply refers to someone who is studying, without specifically highlighting any relationship between this individual and a teacher or school. It's more general, often being used to refer to someone who acquires knowledge beyond formal education environments.
Soy estudiante de psicología.
(I'm a psychology student.)
Hay muchos estudiantes en la biblioteca.
(There are many students in the library.)
Mi hermano es un estudiante autodidacta de la historia europea.
(My brother is a self-taught student of European history.)
Summary
While there is significant overlap, typically alumno refers to someone enrolled in a structured educational context guided by teachers, while estudiante has a broader application. Anyone learning or studying, whether through formal education or independently, can be an estudiante.