Torchwood has always been a show that his been in the shadow of Doctor Who. Torchwood, no matter how fun, can never hold a candle to legacy that is the good doctor. The show has usually seemed to have the same spirit as Doctor Who, however. This is easily seen in the style of aliens. Of course, there also the issue of campy humor. With Torchwood, there is a notable departure from the spirit of Doctor Who. That comes in the season known as Children of Earth. It was a good thing. It was Torchwood staking out its own identity for once and for all.
The third season of Torchwood centers on an alien race only known as the 456. Most of the aliens in Doctor Who and Torchwood tend to be humanoid, with the notable exception of the Daleks — which look more like squids driving their studded tanks with toilet-plunger-like weapons. The 456 are not humanoid in shape. They do not even breath oxygen. In fact, they require a special atmospheric tank to even make an appearance on earth. This makes them one of the most truly “alien” species to ever appear on Doctor Who or Torchwood.
As a result, The Children of Earth season of Torchwood marks a notable departure from the Doctor Who universe. The season is more sinister, and as a result, the show seemed to be much more independent from Doctor Who. Unfortunately, they show didn’t last much longer after that. There was Miracle Day, but it can be safely assumed that Torchwood is now on hiatus with an uncertain future. This is a sad thing. Children of Earth and the 456 marked the show as growing independent of merely being a lesser Who spin off.