Why do companies offer internships or apprentice and which of them is useful for students?

Internship is offered by an organization for a limited period to freshers. The students or graduates look to gain relevant skills and experience in a particular field. Internships are used to see the interest of the interns in the work of the company. The internship is of wide variety. It can be paid, unpaid, and partially paid. Virtual internships are also growing in which the interns work from home and presence at work-site is not necessary. Internship is most common to medical graduates, generally in government agencies.

Apprenticeship:

Apprenticeship is on the job training for the freshers. It enables the apprentice to get the experience of the job. The training is generally done while working for the employer. It may last after two years or more, it is generally paid or partially paid.

For medical students, internship is more useful. Their training is full time but not as rigorous as apprenticeship. The apprenticeship is common in non graduates or less educated persons in the trade such as tailor mistries, mechanics and many more. It usually begins at ten to fifteen years of age. Their work is rigorous. 

As such internship is useful for graduates or more educated students and apprenticeship for less educated persons.