simply because there's less suppression, more healing, less sides, different properties, etc... some people don't want as much size as lgd is capable of putting on and although you can cut with lgd, osta is easier to cut with... they have similarities but still possess different qualities as well... what you run depends on what your goals are, just like anything else... you can run them both together as well if you want... it just depends on what your wanting to accomplish... look at it like this... how do you decide between winstrol and anavar? they possess a lot of similarities but winstrol is stronger but has more sides... people stack them because although similar they possess different qualities as well... same concept, different products... it just depends on the person and their goals from the stack bro...