I think that Roll Back is just away of taking you back to where the model was in it's timestamp build history without losing the rest of model, for what ever reason, perhaps just to help show someone else the process by which you had to go thought to get the model that did. While Edit Feature requires that you roll back in order to get to the feature that you wish to edit. They may look similar, but can be used for different reasons.
The "edit" function allows you to alter the parameters of the feature, the model is displayed in its current state.
The "edit with rollback" function rolls the model "back in time" to show it as it was when the feature was first applied. This is useful when editing features that consume objects.
As an example, create a new model. Make a block feature and a cylinder feature; make sure the solid bodies interfere. Subtract the cylinder from the block (make sure the "keep target" and "keep tool" options are turned off in the settings). Now use the "edit" command; note that you cannot deselect the tool that was subtracted from the block. The cylinder has been consumed by the subtract feature and is no longer available in the part file. Now try the "edit with rollback" command. The feature before the subtract is made current and you are editing the subtract feature just as it was when it was first applied. You can deselect the tool body and select a different one, if desired.