Cabinet costs are a large portion of any large-scale LED project. Knowing the right application is important
As with all the four basic factors, this choice again has a large effect on cost. Outdoor displays are able to contend with a wider range of temperatures, have a housing that can be out in the weather, and are bright enough to overcome sunlight.
All of those things cost money. And the decision is not so much a luxury as a necessity based on your location. For the most part, anything with open air access needs to be an outdoor display. Indoor displays are generally only recommended in an enclosed and climate-controlled venue.
There is some room for discussion in some instances. If your venue is covered, but open-air, you will still need a display that can withstand a wide range of temperatures. But the brightness may not need to be as bright as it would need to be out in the sunlight. And it may not need to be weather-resistant to rain and so forth.
Obviously, any kind of street signage uses outdoor cabinets and LEDs. These are 24 hour, constant-use workhorses that can't use shortcuts to save. Sun or clouds, wind and rain, the display has to continue putting out its message.
The main takeaway here is to not try to repurpose an indoor display in an outdoor application, even if covered. There are important differences in construction and the correct type of display will last a much longer time in service.
Almost any vendor has both kinds of product lines. And again, almost every vendor deals with these issues differently. So the more detail you can give them early, the closer your quote will meet with reality in the end.