I expect a lot of posts on this thread but I'll throw a few things out there. Who knows, maybe some of it will even be correct.
A low profile cutter generally reduces kickback risk and vibration, but at the cost of chip clearing ability, ease of sharpening, and often performance. Something like Oregon 33LG is a regular .325 chassis with a low profile cutter.
Low profile 3/8, sometimes referred to as .365, is both a low profile cutter and a lower profile drive tang. This has the same benefits and drawbacks above plus the low profile drive tang allows for smaller radius sprockets which reduce kickback potential (nose sprockets) and reduce required torque from the engine (by allowing smaller drive sprockets).
Narrow kerf technology is pretty straightforward. Taking less bite out of the wood requires less power and allows for lighter bars, but doesn't really work for larger applications. As far as I know this is only available in .325, but low profile 3/8 might also be a narrower kerf than normal 3/8, I'm not sure.
As far as .325 vs 3/8: if your clutch has a rim sprocket, these are 7 spline and you can't really get less than 7 teeth on a rim sprocket. With 7 teeth the drive tangs fit in between the keys on the spline. Since .325 will have smaller radius than 3/8 with the same number of teeth, the engine needs less torque to pull the chain. However, since .325 has proportionally more cutters per inch of bar, who's to say which is better. It is likely that having closer, smaller cutters makes for smoother cutting in smallish wood.
...but now I'll sit back and watch as most everybody here has more experience than I in such things
