Conventional usage here seems to be DME = Dry malt extract, while LME = Liquid malt extract.
However, I was just reading Designing Great Beer, and Daniels calls DME "Diastatic Malt Extract". As in, DME has enzymes and could be used in a partial mash. Is he using DME in the same way it is used here? Is dry ME in fact diastatic? If so, how much? I guess it would be easy enough to test; just mix some DME with some crystal malt at 150F and see if the starch gets converted. Anyone tried this?
In other news: different extracts have different levels of fermentability. Some stall out at 1.020; some go down to 1.006 (from the same OG, with the same yeast). Some brands have corn syrup added, apparently. Flavor profiles can be different... Do you test your extract? Daniels suggest doing a small scale test when you try a new brand of extract. Liquid extracts have just the right amount of water present to promote browning (Maillard) reactions. How fresh is your extract?
On a side note, he does also point out that many medal winning beers have some percent of extract in them, but always with some grain too.