Bi is the person who has attraction on GENDER : Male and Female . Pan is the person who has attraction not necessarly on gender , gender doesn't matter , doesn't matter if you're a boy , a girl , an animal , etc This is what i heard and read in my life , didn't search etc.
There's basically not a whole lot of difference between pansexuals and bisexuals. The differences are mainly political and get to be very contentious. This is commonly because bisexuality gets to be defined as "being attracted to men and women," where "men" and "women" are understood solely in cisgendered terms, whereas pansexuality gets to be defined as "being attracted to many or all genders." There gets to be this, "bis don't date trans people, but we do" savior narrative, which some of us who are bisexual (or, gasp, trans ourselves), take issue with. For my part, I consider myself bisexual, but I'm happy to date people all along the gender spectrum or outside of it. I just chose to call myself "bisexual" instead of "pansexual" for linguistic reasons; bisexuality has been around as a term for a long time, and people readily understand what it means. People don't know what pansexuality means. In fact, the poster just above me made reference to zoophilia. I am not going to define for pansexuals what their sexualities are, because that's fraught with ethical difficulties. I would hope they extend the courtesy to me. We're multisexuals. We love fucking people...