Both are independent tags.
Groping is merely the act of groping someone:
- Groping [Sex act involving groping anothers body.]
Sexual harassment is more about coercion:
- Sexual Harassment [Sexual coercion, or the unwelcome/inappropriate promise of rewards for sexual favors.]
In short sexual harassment can be a lot more than just groping, and groping can be done without coercion in which case wouldn't be sexual harassment.
Sexual harassment is not just rape or blackmail
either.