What counts as smart glasses?
Smart glasses are eyewear with an electronic job beyond correcting or shading your vision. That job might be playing sound, taking photographs, showing text or displaying a computer screen. The name alone tells you surprisingly little about what you'll be able to do.
Start with the input and output
We find it easier to describe the hardware in ordinary verbs: hear, speak, capture and read. A microphone receives speech. A camera receives images. Speakers deliver sound, while display optics put information in view. Software connects those parts to a useful task. A frame can have several of them, but none follows automatically from another. In particular, a camera does not imply a display.
Suppose you want to follow a recipe while cooking. Spoken instructions need audio output; keeping the ingredient quantity visible needs a display. Filming the cooking needs a camera. Writing down that one task removes more confusion than comparing a dozen products all labeled smart glasses.