Different Species Or Just A Variation?

[GAB99]

hi i got 2 otos for my tank on monday and have noticed that the bigger oto has a full black side stripe while the smaller one has a line only up to the base of the tail. he then has a black blotch as if the stripe was severed. they also both have different tail patterns and the smaller one has a sort of peppered main color, ill try to get pic tomorra it almost 1 here.