I want to experiment with oak, so I've been re-reading the oak barrel
chapter in Pambianchi's "Techniques in Home Winemaking". Barrels are
too big a step for me, so I skimmed until I got to the part about oak
chips. He says that oak chips, "do not add any significant amount of
tannins, and as such, cannot be used for ageing wine."

I don't understand this. If wine takes up tannins in the oak of
barrels, why would it not take up tannins in exactly the same oak that
was ground up into chips or sawdust? Is it a question of contact time?
Pambianchi recommends 1-2 weeks, and I know that barrel ageing occurs
over months or years. So would the wine take up tannin from oak chips
over several months? Is there a downside to this?

Finally is there a difference between oak tannin and grape tannin (from
the packages for sale at homebrew shops)?

Erroll