No, they're both sex characteristics. It's just that there are individuals with sex chromosome aneuploidies who will develop a female phenotype, e.g. X0 (Turner

No, they're both sex characteristics. It's just that there are individuals with sex chromosome aneuploidies who will develop a female phenotype, e.g. X0 (Turner syndrome) and XXX (trisomy X), and also XY individuals where the Y chromosome is deficient in specific ways, e.g. Swyer syndrome.