In theory: Bisexuality is attraction to more than one gender, while pansexuality is attraction regardless of gender. For example a bisexual person could be attracted to women and nb people but not to men.
In practice: Mostly synonyms, some years ago ‘pansexual’ was kind of a buzzword to mean ‘inclusive bisexual’ (as in can also be attracted to trans and nb people), but I haven’t met a bi person that wasn’t ‘inclusive’ or that wasn’t attracted to a particular gender like the example above.
In theory: Bisexuality is attraction to more than one gender, while pansexuality is attraction regardless of gender. For example a bisexual person could be attracted to women and nb people but not to men.
In practice: Mostly synonyms, some years ago ‘pansexual’ was kind of a buzzword to mean ‘inclusive bisexual’ (as in can also be attracted to trans and nb people), but I haven’t met a bi person that wasn’t ‘inclusive’ or that wasn’t attracted to a particular gender like the example above.