While this game is a bit more advance-wars like than most, I still seriously hate how any military strategy game is said to be 'advance wars-like' Yeah, sure, so you've never played a military strategy game aside from Advance Wars, we get it. Now shut up and let people who've actually played more than one game in the genre describe it.
Anyway. Endwar is more scenario-based, and it does look a bit like Advance Wars at first glance, yeah... it's a hex-based strategy game where you only have so many units to win each level. Even on levels where you can construct units, you have a very specific number of resources in the depots, and it does not increase or recover.
It has an unusual turn-based system where one side attacks while the other side is moving (this is not in 'realtime', though -- your enemy enters their attacks at the same time as you're entering your moves, then once you both hit 'done' their attacks are resolved before your moves are, so units that they kill never actually get to move. Then you switch roles.) Your units get support from units around them.
The difficulty is pretty high, since you can't just pump in more units when you make a mistake. It feels pretty similar to that Panzer Tactics game from a while back, really.