Is there any difference between man and woman anus?

Yes, There is a difference.

Medically, the women anal external sphincter is 1.5 mm smaller than males.

Physically, a woman's anus is tighter, softer & more elastic than males. The ratio of sexual nerves ending is also higher as compared to males.

The nature of woman sexuality is normally receptive and thus ladies enjoy anal sex reception much more than males.

The soft and elastic anus along with receptive sexuality makes anal sex less painful for women as compared to men.