Indoor strains

Why are some strains classed as indoor ? What is going to happen if I grow them outside ?

Go to any of the major on-line seed sites (attitude, Herbies, etc) and you can do a power search for indoor strains. I may be wrong but I think the main diff is that some strains won't do as well indoors, maybe grow too tall, etc. I would guess you could grow anything outdoors. But why look for an indoor variety if you plan to grow outdoors?

I wanted to see what the difference is in potency and yield . Cheap light also

Possibly as they cant deal with the stress from outdoors (temps/bugs/etc)