I use bi personally, but pan people argue that they're more than two genders and they are attracted to all of them. I use bi because my sexuality is dualistic -- I have both heterosexual and homosexual attractions. The two are effectively synonymous.

I’m neither so take this with a cup of salt:

Originally they were the same. Pan (and some others) faded from use and was largely forgotten.

When it first came back into use, there was a lot of “you’re attracted to both genders; we’re attracted to all genders” but this got a lot of pushback as being bi-phobic because it paints bisexuals as being transphobic (although if you really think about it, the accusation that this is transphobic is itself transphobic as it implies trans people are not included in “both genders”. Perhaps enby-phobic would have been a more appropriate accusation).

These days the generally accepted distinction is that pansexuals are attracted to people regardless of gender, as in gender plays no part, as opposed to bisexuals who may (or may not) be attracted differently to different genders.

What's the difference between emocore, metal core, hard-core , speedcore and death jazz?

People like to pick their own labels.