Something that cropped up in the recording of an upcoming Meeples podcast: the difference between factions in settings.
There's kind of a scale: at one end we have most any war on Earth, to a greater or lesser extent. The factions are all fundamentally identical (like, duh, human!), and for the most part their technologies are identical or close to it. Sure, we can find counter-examples, such as (say) German tanks vs Polish cavalry, English longbows, but, to be fair, most of those are simply one side not catching up with the other, rather than anything deeper. At the other end, Spartan's Planetfall is a great example (and so, to a lesser extent, is 40K), where the factions are technologically vastly different to the point of having gone down completely divergent development lines (and races), and the core factions pretty much do not share any tech within the context of the game.
It's another design decision, I guess. How 'alien' are your factions to each other, both in terms of species, and almost as interestingly, technology? And you're not restricted to the endpoints of the line: for example, let's imagine a humanocentric setting where the raw materials to do anti-gravity and Battletech-like are artificial muscles ('myomer') are both rare. Divide the humans into two: one faction controls most of the AG raw material, one the myomer, and has for long enough that their technologies have evolved to match - one side uses grav-tanks, the other 'mech walkers.
Personally (and this is very much a personal opinion), I like to stray towards the 'same but different' end. This may be something to do with the fact that I'm fond of subtlety: I like the idea of being characterised by difference, rather than defined by it.
Anyway. That's today's pondering, brought on by running out of podcasts on the train back from London. Enjoy :D