The best known differences are as follows:

Sephardim are not particular about the couple sharing a seat that moves during niddah.
It is customary to take a bath as part of the chafifah. However, a woman can take a shower rather than a bath if she assures that she washes all parts of her body and washes her hair and all body folds in warm water.
The basic number of bedikot during the seven blood-free days is two each day. If there is a particular problem, the number may be reduced. A specific question should be asked.
Certain Sephardic communities require a four-day rather than five-day minimum before the hefsek taharah.
Women of certain Sephardic communities generally shave pubic hair prior to mikveh use.
In certain Sephardic communities, a woman makes the bracha on immersion while wearing a robe, before entering the water of the mikveh. She then disrobes and immerses.

However, “Sephardim” is a broad category that includes women from many different countries with different customs. Therefore, if trying to determine the correct behavior for a particular woman, it is best to ask a rabbi from the relevant community or provide us with more details. Furthermore, when dealing with a marriage of a couple of different ethnic backgrounds, the couple should check in with their rabbi as to which customs they may follow as a couple and which customs they may follow as individuals.