What is the difference between indoor and outside cables?

The difference between indoor and outside cables
Generally, outside cables are designed to resist water penetration by using a gell fill or dry water-blocking compounds and a polyethylene jacket. The new dry cables are getting very popular, since they can be made as distribution types which are easier to terminate. Many also have a PE jacket over a UL-rated PVC jacket so you can bring the cable into the building, strip off the outside jacket and run it anywhere in the building (not the 50 feet limit of PE.) Indoor or premises cable must be rated for flame retardance for safety and to meet code.

If you have a 50 microfiber backbone, can you use 62.5 fiber jumpers on each end?
On the receiver end it is OK, but on the transmitter end, the larger core of 62.5 into smaller 50 micron fiber will have losses of 2-4 db.
If you have a 62.5 fiber backbone, can you use 50 micron patch cords?
Same as above, except the excess loss is at the receiver end. In both cases, the losses depend on the modal distribution in the fiber, a result of the source output and the number of connections.