they are both steroidal inhibitors however,
6oxo- blocks aromatase but keeps estroidal the same and increases test with no change in SHBG
6bromo- blocks aromatization but lowers estroidal, im not to sure about the SHBG. at high doses of the alpha isomer it can potentially cause shut down (but i have not seen this in anyone who has used it) however the Beta isomer has no affinity to convert because of the steric strain on the molecule.