There are so many oddities in their behaviour, during and after they placed the bombs, that makes it difficult for me to categorise them as conventional terrorists. Maybe it's merely because the younger one looks so young, and acts like a kid on his twitter, that we want to believe he was manipulated in some way and that he didn't want this. Personally speaking? I don't think that is playing a large part in my attitude but I get the impression we may see a story emerge that goes beyond the typical terrorist plot in terms of their motivations. The younger one grew up in the states from a small age. People are naturally curious as to how/when he became radicalised.
Remember the original photos? He didn't even think to hide his face, whereas his brother came with shades and wore his cap forward. It's no coincidence the photo of the 7-11 released is of the White Hat brother; he was the one most easily identifiable. Is that naivety? Arrogance? And then to give yourself up to the police later? What kind of Jihadi is that? He apparently, unlike his brother, did not wear an explosive vest. We don't know much yet, but of what we do know, there is certainly a distinction between the two.