However one of the main differences in the latest iterations of the franchise is that for now, Rock Band 4 still does not have online multiplayer while Guitar Hero Live does. The good news though is that Harmonix has not taken the feature off the table and in a recent blog post, explained their decision as to why they have not implemented it yet.
According to Harmonix, the different combination of instruments means that online multiplayer will be a more complex endeavor. “There is a ton of testing necessary as well technical back end to work through in order to provide a fun, stable experience.” To that end, Harmonix also mentioned that they will be sending out a survey to gauge the response to online play, and to determine what gamers want.
Unfortunately this does not give us any idea as to when the feature will be implemented, but at the very least it is still being considered because as Harmonix states, “Adding this functionality is very much on the table but we’re not yet sure where it fits in our roadmap.”