Getting same results with reverb on a send as an insert

I inserted a new stereo bus to a project, but noticed that a soft synth track that was routed through it had its sound slightly colored, even though I had added no effects so far to that new stereo bus.
 
This was with the send level at 0.0, so I guess its just a doubling somewhere of volume right, as the sound is being heard in its normal soft synth track, and in the send track?
 
Then I tried a test with a reverb on a send and as an insert, and I couldn't get things to match at all.  The sound was different for example at 100% wet reverb on an insert as it was on a send at 0.0 (at 100% wet).     What's the logic to that, is it how it should be?

Thanks Karyn - yes, that's exactly how I understand it.    So why the difference in result with the reverb as a send, compared to an insert?
 
I made a test :   track with reverb as an insert played back, then same again using this time same level reverb as a send.   The result was louder when it goes via a send, all else being equal.   Why is that? 
 
And also when I route a track via a send that has the reverb disabled (ie no reverb) the result is still louder - it seems that there is the sound from the main track, plus the sound from the send track (even without effects) and the result is louder.   But its not just "louder" it sounds like 2 tracks together, so there is some kind of "thickening" of the sound (that is with no reverb) ... is that how its supposed to be?  

^^^^
 
You'd typically have to set the reverb plugin's internal mix value differently when used as an insert in the FX Bin vs. a send (bus) in order for the results to match.