You might be looking at specifications of different kinds of fiber optic cables - singlemode for outside and 50 mkm multimode for the inside.
However, in reality the inside cable's attenuation is, in fact, higher due to higher number of bends the cable endures being laid out in a building, many a sharp bend. Every bend adds attenuation to the total loss budget.
Outside cables, on the other hand, are usually laid in straight paths and so the bend-induced attenuation is not such a big concern.
Dmitri Abaimov, RCDD