I am a bisexual trans woman. I am attracted to men and women, which includes trans men and trans women. I am not sexually attracted to nonbinary nor genderqueer people. If I were, I would label myself pan.

I will date straight men, lesbian women, bisexual men and bisexual women. Which makes sense, because gay men and straight women would not be interested in dating a trans woman, so it's mutual.

Pansexuality is essentially a flavour of bisexuality that doesn't put emphasis on gender presentation or identity. But gender presentation is irrelevant to actual sexuality, which is (by and large, as long as someone isn't intersex or transsexual) whether or not you have a penis or a vagina, and which of those is a prerequisite or a deal breaker in seeking a sexual partner.

The way I've come to see it is that pan is actually on the attraction spectrum rather than the sexuality one, though unfortunately, its creator(s) decided to apply a 'sexual' suffix to it, which makes it read as a sexuality.

So when it comes to sex (what bits you have, what bits they have) you have asexual (no interest), bisexual (interest regardless of sex), heterosexual (other sexes only) and homosexual (same sex only.) When it comes to gender based attraction, you have gay (same gender) straight (other gender) and pan (any gender.)

To a point, pan acknowledges that sex isn't always a binary, but I still see it as primarily about gender presentation attraction. I think some people see it as providing more options than 'bi', which is strictly a merge of same and opposite sex interest. But returning to the Greek roots, 'hetero' means 'other' or 'different' rather than 'opposite', so heterosexuality is interest in sexes other than your own, rather than opposite, and bisexuality can combine homosexuality with heterosexuality to adequately cover all bases.

My GF had a great way of defining them. She's bisexual, partly because she feels different attraction to men and women.

I'm pansexual because I'm attracted to a person, what parts they have isn't important to me.

I do think bi and pan are nearly interchangeable. I think bi can mean attracted to two or more genders/sexes. Pan means all.

Don't know.

Pan holds gender identity included. So some bis are not pansexual but mostly what @katrik said

And thanks for asking instead of just assuming or not caring at all

Depending on definitions used, the answer can vary. Personally I use bisexual as an umbrella term for anyone with sexual attractions to more than one sex. Using this definition there is no meaningful difference between the two.

A literal dictionary definition of bisexuality, due to the prefix bi-, is sexual or romantic attraction to two sexes (males and females), or to two genders (men and women). Pansexuality, however, composed with the prefix pan-, is the sexual attraction to a person of any sex or gender. Including transgender