What is the difference between indoor and outdoor Type 2 magazines?

Under 27 CFR 555.208, outdoor Type 2 magazines must be bullet-resistant, fire-resistant, weather-resistant, theft-resistant, and ventilated. Indoor Type 2 magazines must be fire-resistant and theft-resistant; bullet and weather resistance may be omitted only where the enclosing building provides protection from weather and bullet penetration. Indoor quantity and occupancy restrictions also apply.