Augmented reality overlays generated content onto a live view of the real world, most often through the camera of a phone the visitor already owns. The distinction from virtual reality is that the real environment stays: AR adds to what you see, VR replaces it.
In retail and signage the useful cases are narrow but genuine: showing how a product looks in the buyer's own space, putting instructions on the object being serviced, or turning a printed surface into something animated. All three share a trait: the physical context is what makes the digital layer worth having.
The caveat is the download. Anything requiring an app install loses most of its audience at the moment of asking, which is why web-based AR that opens from a QR code outperforms a better-built native experience nearly every time. Judge an AR proposal by how many taps separate curiosity from the effect.
Also budget for the content, not the technology. AR platforms are commodities; a convincing 3D asset of your actual product is not, and it is what the experience is entirely made of.