There is no *real* difference between "indoor" and "outdoor" strains. Technically, all plants are outdoor plants. The term "indoor" simply means it is well adapted through selective breeding to grow in an indoor environment (moreso than other strains in other words). It by no means indicates that a strain can't be grown outdoors. The indoor / outdoor trend in labeling strains wasn't even invented until the 80's.

See "Sensimilla Marijuana Flowers" by Jim Richardson and Arik Woods (published 1976). This work has been considered a turning point in MJ genetics by many, including Robert Connel Clarke (famed cannabis chronicler). In the 70's and 80's the "Sacred Seed Company," a clandestine breeding co-op in California, began the sensimilla revolution and started the selective breeding wave that has since spread across the globe and migrated largely to the Netherlands. Only during this time period did the terms "indoor" and "outdoor" come about, only to distinguish which strains could be easily bred in the limited spaces of indoor setups. Before this, there weren't many different designations between strains, as just about everything in the US was sativa (indica species subtypes weren't introduced in to the US until around '74).

Just a little history of the herb for all to enjoy...