Daniel, there is no difference between a Baster and a Dutch Oven. I think that when Griswold introduced the basting rings on their dutch oven covers they came up with a new name to tout the basting feature. Perhaps, after a short time of up to a few years, a return was made to Dutch Oven as most people probably knew the name of that pot to be a dutch oven. Only my guess on the name change.
As far as matching your top and bottom have a look at my Cast Iron Cookware News here on the site somewhere as a PDF. On page 91 (June 1991) is a short article about dutch ovens/basters and slant/block TMs and what goes with what.
Covers came with Baster or Dutch Oven and with the slant TM. Bottoms also came with Baster or Dutch Oven on them and with block TM. I'm not sure if the bottoms came with Dutch Oven and slant TM. My conclusion is that it's very possible that Griswold did mismatch Baster and Dutch Oven parts (top and bottom) and slant and block TM's on a piece.
Any pattern number listing that says a pattern number is for a "Dutch Oven" might also mean that the same number is for a "Baster" also since the same p/ns were used for both of the 1920 patented versions.
Steve
