What is the difference between a 4 year sandwich course and a 4 year non-sandwich course in fashion design?

I understand there is obviously a year in an industry placement of some sort, but that leaves an extra year for the normal course? does anyone know what this is for? actually what is a sandwich course? im confused. no smart ass answers . thankyou in advance for your replies x
Answer
Sandwich course mean a placement course. u mite hav a placement or work xperience within ur course. but i dont know y there is a 4yars non-sandwich course.