If a place is crammed with things or people, it is full of them, so that there is hardly room for anything or anyone else. The house is crammed with priceless furniture and works of art = bursting, packed
If people or things are crammed into a place or vehicle, it is full of them. Between two and three thousand refugees were crammed into the church buildings. = packed. crammed with/crammed full of sth completely full of things or people = packed