Formal:
* Alumnos: This is the most common and neutral synonym for "estudiantes".
* Discípulos: This is a more formal and literary synonym, implying a sense of learning and following a teacher's guidance.
* Aprendices: This emphasizes the act of learning and acquiring knowledge.
* Académicos: This is a more specific term referring to students in higher education.
Informal:
* Chicos/Chicas: This is a casual way to refer to students, especially in a school setting.
* Chavos/Chavas: This is a more slang term for students, common in Mexico and other parts of Latin America.
Other options:
* Pupilos: This refers to students who are under the care and guidance of a teacher or mentor.
* Egresados: This refers to students who have graduated from a school or program.
* Estudiantes de postgrado/graduados: This refers to students enrolled in postgraduate or graduate programs.
To choose the best word, consider the context and the level of formality you want to achieve.