Pansexual is often confused or conflated with bisexual, as both terms cover characters who have sexual attraction, romantic love, or emotional attraction toward people of multiple sex or gender identities. The primary difference is that a bisexuals are attracted to both men and women, while pansexuals are attracted to all. In this case, since we’re talking about TV, we include aliens (though not vampires and shapeshifter) as part of pansexuality.
Much of the difference in terms comes with age, as the term pansexual is relatively new when compared to bisexual. Characters listed as pansexual have either expressed the term themselves as part of their identification, or they’ve slept with aliens.