Rob, I would say - very simplistically perhaps - that power comes from the diaphragm and control comes from the throat. You'll find lots of discussion on the 'net, I'm sure, about 'head tones' and 'chest tones' and all other sorts of technical stuff. In my practical experience, (and my voice has sometimes been likened to a junior foghorn) singing from the stomach is what gives you projection (not to be confused with volume).

One of the problems about singing sitting down - which is what we tend to do in singarounds and session, and even folk clubs - is that there is less internal freedom to let the chest, stomach, diaphragm, etc., do their job. I've spent most of my musical life standing up to perform in bands - albeit with a mic - and you get far more projection, IMO, standing than sitting.

The lack of an audience - and thus adrenalin - when recording at home can also make it the performance less lively and dynamic than it would be live.