Are the dragons about the same as in OD&D? damage, HP, etc..?
I would say dragons are "about the same", yes. If anything, DD dragons can be somewhat more variable.
The main difference is really that (as per the SRD) DD dragon hit dice are rolled to determine hit points, rather than being assigned by age category as they are in OD&D. The exact numbers of hp are, on average, reasonably close.