It's not just printing, it's maintaining / fixing jams / replacing / etc. for both ticket machines (self serve and staffed machines) and for ticket readers - with business logic being that motivating less use will cause costs to go down, more than (but not excluding) covering the actual running costs of keeping the older technology running.
Additionally (though I don't know that it's relavent to the two figures you quoted), the paperless system is flexible in that it can measure all the journeys you take in a calendar day and then charge you whatever the lowest suitable fee is at midnight - whether that's a single or a return or a day pass or an off peak something or so on. Whereas with paper tickets the person needs to decide up front which option will be cost effective based on the trips they're expecting to take, which often is a cause of paper TFL tickets working out more expensive also.
Additionally (though I don't know that it's relavent to the two figures you quoted), the paperless system is flexible in that it can measure all the journeys you take in a calendar day and then charge you whatever the lowest suitable fee is at midnight - whether that's a single or a return or a day pass or an off peak something or so on. Whereas with paper tickets the person needs to decide up front which option will be cost effective based on the trips they're expecting to take, which often is a cause of paper TFL tickets working out more expensive also.