Hi Dave and Brandan,
You'll find Planetstrike is like normal 40k, but with much more specialized forces. You'll know if you're the attacker or defender before you make your list and can then make accordingly. If you're the defender, your list will probably have a good amount of heavy choices (you're allowed up to 6 as defender, if I remember correctly) and good defences. You get to choose how you set up the board as defender, and can put as much or as little cover on as you want. You put the bunkers, the bastions, the trenches, everything to your liking.
As attacker, your troops will most likely be fast moving and strong striking. As an example, for my Space Marines as attacker everything was in Rhinos or had jump packs, everything that had melta bombs could (bastions are armour 14 all around, had to do it somehow). I had power fists, etc. up the wazoo. You get the idea.
You also get strategems, like Apocalypse, based on whether you're the attacker or defender. There are currently some glaring problems with the rules, favouring the attacker heavily. But a fair amount of house ruling has solved some, whether or not it is used in your game. It's a fun time, giving a much different feel to the game than your standard battleline game.
