According to recent laws, there are few differences between harassment in cyberspace and in reality. The difference comes when the term "rape" comes into question.
Sexual harassment in reality is both verbal and physical, in cyberspace, harassment is obviously only verbal. Both, however, cause severe emotional stress. Saying "you are hot" to a co-worker in person is no different than that being said via instant message.
There is a difference when it comes to definining rape - it can only be physical contact and would likely involve some sort of physical injury or force that would not be possible online.
The flight or escape methods are different for these cases in person and in cyberspace. When violated physically, there can be more fear or intimidation possible when in close contact with the violator - this is not as influential when online. There is less consequence of harm when online.