Genderqueer
A gender outside the binary — the older, more political word for it.
Genderqueer arrived in the 1990s, well before non-binary entered common use, and it carries that history. It was coined inside activist spaces and keeps a deliberate edge: queer here is reclaimed, not neutral.
Many people use genderqueer and non-binary interchangeably. Others choose genderqueer specifically because it refuses the tidiness of a category — it names a relationship to gender rather than a position within it.
Which word someone picks often tracks generation and politics more than any difference in the gender itself.