The properties of wood may be different, yes (I believe Spruce was the wood in question in those tests), but the mechanism through which glues work is the same, and the basic structure of wood is the same. Of course, you've got oily, hard to glue woods as well, and those may requires some de-oiling (although again, there be arguments on that front), or maybe the use of epoxy (which does like a rougher surface).
Gluing Metal is a completely different subject, natch. I've glued silver for inlay (good ol CA), but I'd probably go with epoxy or polyurethane for dissimlar materials.
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good insight. thanks again.