Ego death and stream entry is it the same thing?
I wish it were so complete.  Stream entry, while a major event in one's practice, is by no means the death of the ego.  In fact, it only releases one from the lower three fetters (e.g. belief in a self, doubt, and attachment to rites and rituals).  There's much more to go.  I'd go so far to say that it's not until one becomes an arhant that the "ego", as we understand in the Western sense, is finally put to rest.

It's important to understand, however, that "stream entry" is category term for a collection of insights.  While these insights can happen as the result of a single event, that event and the experiences surrounding it like feelings of oneness, visions, and the like are really inconsequential.  What is important is the shift in perspective that follows.  This is fundamentally what distinguishes Buddhism from other mystical traditions.