I'm gonna be honest, and I will try not to offend anyone, but this is what I think.

I think that pansexuality and bisexuality are the exact same thing.

Pansexuals is described being attracted to all genders, but in actuality, gender really plays no role in your sexual attraction. Sexual attraction has to do a lot more with biological sex rather than gender, and as we know, there are only two sexes. Of course, there are intersex people, but being intersex isn't necessarily a third sex itself. Being intersex means you have both male and female reproductive organs, and intersex people can still have a leaning towards male or female. If gender truly played a role in how someone is attracted to someone, it would be impossible for a straight male to be attracted to a trans man. However, it's not because they are attracted to the fact that the trans man is biologically a female.

With this thought in mind, pansexuals prefer to define it as being attracted regardless of gender instead of describing it as being attracted to "all" genders. To me, this seems like it would be similar to being bisexual without a preference. You like men 50%, and you like women 50%, so it seems like it doesn't matter.

Even if something different is implied with this definition, I don't think it should be seen as a separate sexuality altogether, and it should be viewed as more like a "subclass" of bisexuality.