It is general rule that all Offset prints are designed for indoor use or short term outdoor use. Silk Screen - Silk Screen is generally accepted as the best and most durable printing available because the silk screen house has use Air Dry, Heat Dry, or UV Curried inks and in most cases can offer products that will last years outside. Plus the silk screen process can clear coat the images for more UV resistance and durability. Digital printers are all over the map, from no durability at all to 5 plus years in the outdoors. Because of this you need to be very clear as to the life expectance of the product when you are talking about durability.
Most digital prints are over laminated to enhance the quality and durability of the graphic.
Sometimes we confuse this with distance of viewing. You must understand that a billboard can be printed at 12 ppi and it will look fantastic from 200 yards away, but it will look very poor up close. For jobs like banners the output device can be as low as 100 ppi for viewing within 10' to 20'. And all the way to 12 ppi for billboards. The only application that does not follow these rules is Backlit displays.