This distinction matters because I get emails from people trying to bleach what is really thin enamel or genetics. Whitening helps stains better than it changes your basic tooth architecture.
So what is the honest answer?
Yellow teeth can be natural dentin showing through, while stained teeth are often color sitting in or on the surface.
Surface stains usually come from coffee, tea, wine, tobacco, and plaque that was not fully removed. Intrinsic color is deeper. Enamel gets thinner with age, and the yellow dentin underneath shows more.
The part people usually miss
If a cleaning makes your teeth look brighter, stain was a big part of it. If not, whitening may still help, but the result will be subtler. Do not chase paper white if your teeth were never built that way.
My rule is boring and useful: change one thing, watch what happens, and stop if your mouth gets irritated. Teeth respond better to steady habits than to panic routines before weddings, photos, or dentist appointments.
How I would handle it this week
- Take a baseline photo in bathroom lighting you can repeat.
- Keep brushing gentle at the gumline, soft bristles only.
- Do not stack three new products at once, because then you cannot tell what helped or hurt.
Related reading: this guide and this review or article both go deeper on the practical side.