The 120 fiilm is a roll film that is 2 1/4 in wide when used in a Twin Lens Reflex it usually made 12 2 1/4 in pictures on a roll . This film is paperbacked the length of the entire roll. It could also make 16 pictures on a roll. The exact size I do not recall but smaller that 2 1/4 in square.
The 620 film is identical to 120 film except I HAD a narrower lip on the spool. The idea been tha smaller cameras could bee produced. It is no longer made. I have some rolls of 620 Verichrome Pan(ASA 125) from the '70s have not used yet. The 220 film is twice as long as 120. This allows 24 pictures on a roll. It has a paper backing at the beginning of the roll and at the end of the roll. I hope this helps! James Johnston
