No they're not the same (this is raytracing fundamentals - however, it's been a long time since I've been reading up on those). Specularity is more like the shininess of the surface, which defines the amount and location-based intensity of the excident light (the light that is reflected off the surface) where as reflectiveness defines the relationship between incident and excident light. In simple terms:

Specularity is the amount of glow generated by a lighsource on the surface (through surface properties), which can be used to identify hotspots of exposure on a surface. Example: a non-shiny (rough) aluminum kettle in a spotlight carries specular properties.

Reflectivity is the surface's ability to bounce off incoming light in its original (color) spectrum . Example: a mirror is an almost perfectly reflective surface.

To use your examples:

Wood or stone: diffuse
Metal / plastic: diffuse and specularity (but very little reflectivity)
Mirror: reflectivity (but very little specularity and minimal diffuse)

If anyone can offer a better explanation, go ahead (also correct me if I'm wrong).

Googling will also help you quite a bit.

"Finishing in second place, simply means you are the first loser." - PouyaCat 

[edited by - crispy on March 26, 2004 5:01:12 PM]