system
Given the following post, respond as if you're commenting on Reddit:
human
CMV: Pansexuality is just bisexuality

This is not a diss to anybody calling themselves pansexual, this is simply a question of why the term even needs to exist. For reference, I am bisexual myself.

Sexuality refers to what you are sexually attracted to, right? This means you are attracted to penis, vagina, both, or neither. There are no additional parts.

Here's a common definition of pansexual: "sexually attracted to people regardless of their sex or gender." And here's the definition for sexuality in general, "capacity for sexual feelings."

There's an issue with pansexuality in this case. It seems to be implying that people who bisexual stay with their partner strictly because of sexual desire, which is not the case in most people. Bisexuals also like people regardless of their sex, and this isn't an argument for gender. It just feels like a way to further stereotype bisexuals as promiscuous, poly, and/or not able to commit. Pansexuality, by existing, implies that it is more inclusive than bisexuality.

I don't think both terms should exist considering they basically mean the same thing. This argument has nothing to do with gender expression by the way, it is purely for parts, because that's what the 'sexual' means in the words. Please give me alternative views though, I genuinely just want to understand why the term pansexual needs to exist along bisexual.

ETA: There is a common misconception about what bisexuality is. It doesn't just mean cis men and women, it includes nearly every gender/sex that exists. Also, my mind has been changed regarding this, so please stop attacking if you haven't read all of the comments.

ETA2: If anybody would like to have a further conversation regarding this topic or anything you may agree or disagree with, feel free to send me a DM! It's getting a little hard keeping up with the sheer number of comments but I want anyone who has something to say to me to be able to do it!
gpt
Bisexual is just an umbrella term, from which pansexual falls under. Pansexual is essentially bisexuality but more precise. As in, all pan people are bi, but not all bi people are pan. 
The meanings can differ depending on times and who you ask, but generally bisexual people can or can not have a preference towards certain genders. In other words, gender may or may not play a role into attraction.

Pansexual, on the other hand, means that gender does not play a role into attraction.
Just like the other side is omnisexual, where gender does play a role in attraction. 

Both if these fall under the bi umbrella as they are just more specific terms.