A deep freezer can store milk for longer (6 months) than a fridge freezer (3 months) because you don't open them as much.
As to what size it depends on how much you plan on storing. I stored about 3-4 days worth of milk in a grocery bag in the freezer to give you an idea of the space it takes up
Any stand alone freezer will work just fine. The idea is what pp mentioned. A freezer opened less frequently is better for storing milk. I'm donating breast milk and they specifically ask what sort of freezer I've been storing it in.
Re: Freezer for bm
Excuse me for being blunt but isn't a freezer a freezer? They all work the same to keep milk frozen..
A deep freezer can store milk for longer (6 months) than a fridge freezer (3 months) because you don't open them as much.
As to what size it depends on how much you plan on storing. I stored about 3-4 days worth of milk in a grocery bag in the freezer to give you an idea of the space it takes up