The reasons some of them say outdoor is because it may be a plant that grows tall. Try looking for more information with respect to that in the seed's listing. If its not on the site your ordering it from, google the same strain and find the information elsewhere. If you have the space to accomadate a tall plant, or the pain in the ass that it brings with it - go for it! (You can always just flower early). But the yield will be better suited to the outdoor growing environment/lifecycye (veg/flower times). That could be the larger problem, a flowering time thats longer than what you want to wait for. You want a quick turnaround time in most indoor operations because you can't afford the time.