120 film is a larger format than 35mm, and is generally referred to as medium format – digital medium format cameras have sensors that mimic the size of this film. 120 film will actually produce different image sizes depending on which camera you use; the sizes available are 6 x 4.5cm, 6 x 6xm, 6 x 7cm.
The larger format gives you greater ‘resolution’ to play with, and also allows for much more latitude to isolate a subject in a shallow plane of focus with a blurred background. Portraits shot on 120 film can pop so much that they look almost 3D! However, 120 gives you fewer shots per roll to work with (generally around 8 to 16). A medium format setup is also much heavier than a 35mm one – though also more durably built. Neither is better, it’s all about your preference!