When you buy physical you can playit anytime you like if you buy digital they will remove it from the store or even will close the store and you will be never able to play it again.
you need to be able to backup your original physical medium because they trend to wear off and are expensive, using a backup to preserver your original media is a must.
you need to be able to backup your original physical medium because they trend to wear off and are expensive, using a backup to preserver your original media is a must.