Yes. Most carpet cleaners are not made the same as vaccums. They do not have the filtering system for dust that vacuums have. I never heard of a vacuum/carpet cleaner combo. This isn't to say they do not exist. I just never seen one.
We have a Kirby and it has the attachment to make it a carpet cleaner. Works fabulous, too. For the cost of that thing, it should! Plus it better NEVER wear out!! So far, we've had it 11 years.
The kirby has a separate attachment for the shampooer. The dirt portion of the vacuum and the shampooer are totally different pieces. I have a kirby and I don't care for it. I have a dyson also and I think it is far better machine. My dyson was picking up dry cleaning powder from shampooing that my kirby did not. I also have a oreck orbiter shampooer and I love that. It is a dry clean method which is great! I can shampoo the floor and in 30 minutes vacuum and put all the furniture back, no wet floor.