Hi everyone, maybe everyone already knows that, but I haven't figured 
out an answer yet (maybe I haven't searched in-depth enough).

I noticed that some angels die exploding when they are hit in their red 
core (most of them).
However some of them (I remember Shamshel, episode 3 and Ramiel, in 
episode 6 and maybe someone else I forgot?) die without exploding when 
an eva delivers them a lethal hit.

In fact later on Ritsuko and the Nerv guys are seen examining Shamshel 
(they say it's quickly decomposing, by the way), and dead Ramiel is seen 
crumbling over Neo Tokyo 3.

So I wonder, why some angels die exploding instantly, and why others 
decompose? Any hypothesis?