I've got some decent experience with the game (almost all Union) but must confess that my grasp of this area is woeful. I read about Conscripts, about militia demi-brigades, and there is definitely something I'm not seeing, either on-screen or figuratively.
XM - superimposed, infantry with an 'M' - militia, I get that. Instant guys, don't ask too much of 'em. Can magically turn into...something. Can put two of these MilitRegts together to form a demi-brigade, but I'm clueless about this.
LightInf - a little better. Sometimes just appear, voila! Often seen as LI/LI/Militia Bdes. Cool. Not bad for 61. Later on, this observer has seen Inf/Inf/LI - these are the results of the Magic Training Program or, perhaps, the Trainers that I use. Unsure. Confused.
Conscripts - "conscript companies", perhaps? Maybe only that meaning? Raw recruits, strawfeet. I don't see these as elements, do I?
When I build an Inf/Inf/Inf/Cav/Arty in Boston, those are recruits being assembled, I presume? Is this formation, so dear to my heart, a conscript formation when it's ready to be deployed?
I dunno - dunno at all, when it comes to these topics. I just rush warm bodies to their doom, I'm afraid.