[lksteve]

i would argue that a civil war entails a pulling apart of dissimilar groups within national boundaries, whereas an insurgency could be charaterized as an erosion of a national grouping from within...

one could assume (with all the dangers that entails) that you pose a leading question regarding symmetry; that a civil war may tend toward symmetry (or perhaps better defined factions), toward conventional warfare, both on the battlefield and within the diplomatic arena, whereas an insurgency may lend itself toward unconventional warfare (or asymmetrical warfare, to use the current expression) both as a means of prosecuting the military and the political aspects of the conflict...

as to scale, one could be led by your question, that civil wars may be fought on a scale, once again both militarily and politically, much larger than an insurgency...as i state above, civil wars seek to create separate political entities from within national boundaries, where an insurgency seeks to create a new order within those boundaries...