Dad’s short answer: Mostly the same machine under two names now. What matters isn't the label — it's whether the machine extracts. A true extractor sprays solution and immediately vacuums the dirty liquid back out. An old-style shampooer foams the carpet and leaves you to wait for it to dry.

Extraction is the whole distinction

Old shampooers worked the way the name suggests: they applied a foaming detergent, brushes worked it into the pile, and it dried into the carpet. You vacuumed the residue up afterward. That residue is the problem — detergent left in a carpet attracts dirt, which is why shampooed carpet often got dirty faster than it was before.

A modern carpet cleaner is a hot water extractor. Solution goes down, brushes agitate, and suction pulls the dirty water straight back into a separate tank. Nothing is left behind to attract dirt, and the carpet is damp rather than soaked.

Anything worth buying today is an extractor, whatever the box calls it. The word shampooer on a listing usually just means the seller is using an older term.

What to check instead of the name

Whether there's a separate dirty water tank. That's the giveaway. No dirty tank means no extraction.

Whether it has a dry or suction-only mode, so you can make extra passes to pull more water out at the end. That's what gets your carpet dry in hours instead of overnight.

How strong the extraction actually is, which is the spec that decides how long your carpet stays wet. Good drying suction is the difference between walking on the carpet the same evening and roping the room off until tomorrow.

And whether it uses a proprietary formula, which is its own conversation worth having before you commit.

Dad’s Take: Look for the dirty water tank. If the machine doesn't pull the water back out, it's leaving detergent in your carpet.