cameras don't take better pictures, you do
at most, lenses might help taking better pictures, since they're the eye of the camera. the other one eye is yours.
that being said, some cameras have certain features that you can benefit from. some of these can give you more freedom to get the picture you intend to, and i guess that these are the ones that make one camera better than another one. for example, if you want to freeze the movement of someone driving very fast, then a camera with fast shutter speeds as up to 1/8000 will be definitely better camera than one that only reaches 1/500. But as you can see it is you, your needs, and not the camera alone.
then we could also mention some other aspects that can be considered more objective and not so dependant of one's needs, as for example plastic vs metal: a metal body camera is better than a plastic one. and yet even something like this can be questioned: what if i don't want the camera to weigh? then plastic is better!
so... to sum up: it is how much its characteristics adapts to your needs what makes a camera good