The big difference is that Viking culture was built around very regular raiding and war.

I mean, if you look at the endemic warfare of Christian Europe in the same period, the main difference is that the Vikings, as a seafaring culture, had a wider range. The brutality and frequency of warfare amongst squabbling aristocrats and clan structures in Christian Europe was not particularly better, just generally limited to literal neighbors, on account of the difficulty of traveling across a neutral party's land.