There are a couple of serious difference though. Namely - radical Islamists don't operate only on US soil and their victims in Muslim majority countries are much more numerous AND second which is even more important, there is a difference in the stated goals and intentions - the killers in Chicago don't want to spread their vicious version of Islam throughout the world and don't want to kill as many non-Muslims or not-pure-enough Muslims through any means possible.
Don't get me wrong, gun violence and gang violence is a very serious problem that needs to be tackled with utmost seriousness, but the Chicago killers are not looking to maximize their indiscriminate killing count and are not looking to acquire weapons of mass destruction, while if Al Qaeda or ISIS had a nuclear bomb, do you think they'd hesitate to use it on highly populated area with civilians?
That's the biggest difference and that's the reason it should be taken VERY seriously even if the victim count doesn't currently rise to levels of other domestic threats. Where they have most control, there are daily mass killings and executions of innocent people, and if they are not challenged and fought, this cancer will spread and sooner or later they will find a way to acquire even worse weapons and use them against even more people.