Biden's executive order is basically the opposite of what Gabbard rightly supported. Namely, Biden's order demands that trans-women be allowed to compete with biological women in athletics.
I must be frank--this is fundamentally the difference between etiquette and political correctness.
Etiquette allows us to have reasonable conversations about this issue and deal with serious, sometimes uncomfortable realities.
There are some sports wherein biological men and/or trans-women hold little advantage over biological women. Contact sports and sports that demand "explosiveness" as is often said, are not among them. Hormone treatment for (especially) people who went though puberty as a man doesn't change the number of fast twitch muscle fibers. Hormones don't change the size of your heart. Estrogen can increase bone density. Yes, trans-women would be at a disadvantage competing against biological men; but, in general, trans-women have huge advantages over biological women.
Political correctness, at this point in history, would label me and people like Tulsi Gabbard as transphobic for even mentioning that. It would demand that we ignore the biological women who are being erased from the record books and have lost athletic scholarships to trans athletes. Not only are we not supposed to mention the inherent problems that go along with this issue; we're supposed to celebrate actions like Biden's as "progressive."
I won't celebrate Fallon Fox going toe to toe with biological women in an MMA bout.
That's really the difference: etiquette demands nothing more than that we speak the truth as we see it without going out of our way to needlessly be a dick while political correctness demands that we celebrate watching a biological woman getting her skull cracked open so long as we don't hurt anybody's feelings.