Bisexuality – from the Latin bi-“two ” – is often defined as physical, sexual, emotional or romantic attraction for two or more genders, often one’s own and another.

Pansexuality – where pan- means “all, every” – refers to physical, sexual, emotional or romantic attraction to any person, regardless of gender or gender. This term has been proposed in such a way as to more clearly recognize the plurality of genders and identities.

It should be remembered that these definitions are theoretical. In practice, each person experiences his orientation in a way that is unique to him. The choice of whether or not to use a label and the reasons behind this choice are personal. For example, a person who claims to be bisexual does not necessarily subscribe to the idea that gender is binary (male/female) and may be attracted to a person whose gender is fluid. Thus, rather than talking about the differences between bisexuality and pansexuality, it is more relevant to talk about what these orientations have in common, namely attraction to more than one gender.

Sources :
http://biplan.yagg.com/2014/11/09/bisexualite-et-pansexualite-meme-combat/
http://bisexual.org/qna/what-is-the-difference-between-bisexual-and-terms-like-pansexual-polysexual-omnisexual-ambisexual-and-fluid/
http://www.youtube.com/watch?v=Bv5k9w6Hpi4&feature=youtu.be
http://fvsch.com/articles/bi-pan/