What is the difference between a skin tag that’s on the groin area and genital warts?

Big differences. Both are benign. We don't know the cause of skin tags but they are more common in those who are overweight. They do not need treatment and will not spread or be contagious. It is easy to cut off or freeze them off.
Genital warts are caused by HPV virus and can spread and also be contagious. While they can also be frozen they can be more difficult to eradicate. .
Agree with Dr. B. Get HPV vaccine even if you have genital warts. There are multiple types of HPV that can cause warts and genital cancer.