"Pansexual" indicates somebody who loves people of all genders and sexes. It is identical in meaning to "bisexual", and was likely formed through the same thought process that created the Rastafari "inity" from "unity".
The "bi" particle in "bisexual" simply indicates that a person is attracted to both sexes. While there are arguably 3 genders (males, females, and those who associate with neither), there are only two sexes. Bisexual people generally are attracted to both sexes, which includes all genders, which includes everybody.
I can call myself either pansexual or bisexual. Either applies.