There are significant differences in between Muslim scripture and Christian scripture that also account for those behaviours. The difference is not having a better publicist, it's a number of historical and social factors that have gone into tempering the application of Christian doctrine, in combination with different fundamentals of that religion.
There's a reason there are no Jain suicide bombers, there is a reason that Tibetan Bhuddists react to occupation by immolating themselves instead of blowing themselves up. These differences are sourced in religious precepts like martyrdom and jihad. Failing to recognize those differences, you can't even begin to have a conversation on how to solve the problem.
I'm not sure how you can claim to have listened to Harris and still hold the position you just expressed, given how well and how frequently he's argued against it. Unless you have some reasons for disagreeing with him that you haven't expressed there. This would be worth your time:
http://www.samharris.org/blog/item/no-ordinary-violence
As to the differing reactions, look at the evidence for the rationale underlying any particular attack and you can reasonably categorize it as motivated by racism, by some non-religious ideology (political grievance), by religious ideology, or by mental illness, or some other motivation, and often some combination of these things (I'd say abortion clinic bombings have some flavour of both religion and politics, for example). In any given case, you can argue that the media or public reaction is wrong - eg "I don't think this is a case of mental illness, I think that person knew precisely what they were doing and had political grievances they felt were legitimate". But in the case of much jihadi terror, the motivations are largely religious; again, with some flavour of politics mixed in.