In a far and distant future, men and women have become mortal enemies. Each living on seperate planets, an interstellar war is being fought between the two very different peoples. Hibiki, a mere 3rd class worker, finds himself in the middle of a huge space battle, facing the nemesis of mankind: Womankind!
In the early 21st century, insectoid organisms are invading the galaxy, searching for new stars to house their young. Mankind's only defense lies with space cadets such as Takaya Noriko, daughter of a celebrated admiral killed in battle, and Amano Kazumi, the top of her class. With their skill and the power of the mecha known as GunBuster, the girls must help fight to protect the galaxy from total annihilation...
There are no new stories, it has been said -- only old ones which are told in new and interesting ways. I'd say a comparison between Vandread and Infinite Stratos exemplifies this concept quite nicely.
A singular member of gender N is, against all odds, suddenly thrust into an encapsulated society which is dominated by gender Z. Said member of gender N, generally met with apprehension, loathing, skepticism, and/or the same sort of interest one might have in a foreign species, one or two members of gender Z give gender N's representative just enough of a chance to serve as a catalyst for others to do the same. At some point, all hell breaks loose, and ol' gender N is given the opportunity to prove that they're not brainless, walking genetalia.
The entire premise of both series hinges on the politics of gender, status, and rank. Everything is tied together with the standard mecha flair, and many popular moe archetypes are represented -- the high class ojou-sama, the militant feminist, the token foreigner, the heterochromic, etc.
Other than a somewhat heavy reliance on fanservice and CG (the latter of which is, at times, of questionable quality), I've little criticism for either show. Perhaps I'm just easy to please, but I felt that each series told its tale in a fashion that will keep the average viewer compelled enough to finish with a satisfied smile.
There is, of course, SOME divergence, and are plenty of differences in style and delivery to keep things fresh. Still, nothing here is new material. This is not, however, to say that the material presented is sub-par. It simply means that you've heard this story a thousand times. If you've watched one of these titles, you'll see the offerings of the other coming a mile away... and are very likely to enjoy the tale all over again.
In the world of Prestal, Noble men perform noble deeds for noble purposes. All of this is performed under the careful gaze of the Guild, a race apart who live in cities in the sky. We see this world through the eyes of Claus Valca and Lavi Head, as their travels take us above, beyond and through Prestal, and their actions cause ripples that shall never fade.
Last Exile and Vandread were done by the same studio, and they give a bit of similar feeling. In both, the action takes place on big and small vessels, airships in Last Exile and spaceships in Vandread. Some characters are similar, like Meia and Tatiana, as well as the structure of the whole story.
On the other hand, Vandread is a harem/ecchi/comedy show (not that much of ecchi, but still), while you can't expect anything like that in Last Exile (except for a bit of comedy and maybe a hint of harem in one episode).
Last Exile is more serious, and has much better CGI. Give it a try.
Keitaro Urashima is somewhat of a failure. In order to fulfill a promise he made to a girl fifteen years ago, he has tried time and again to get into Tokyo U but has never managed to pass the exam. However, fate smiles upon him and he ends up working for his aunt, managing an all-girls dorm! Living with the feral Kaolla, the timid Shinobu, the sake-loving Mitsune, the blade mistress Motoko and the punch-happy Naru, can Keitaro keep his focus and keep his promise? And will he ever end up meeting that girl from his past?