The difference is that the inactivators permanently stop the aromatase emzyme's production.
Women on Aromasin were more likely to have fractures, joint pain, osteoporosis
, visual disturbances, and diarrhea, while women on tamoxifen were more likely to report vaginal bleeding, muscle cramps, and blood clots.
Femara has been found to have less impact on cognitive functioning that tamoxifen. (I don't know if that would be the case with other aromatase inhibitors/inactivators though.