Probably the most noticeable thing is that they're all heavier/faster than either. The clean vocals are almost entirely gone (the melodic/slow breaks aren't), with a few unexpected surprises. The style is oriented towards more "modern" melodic death metal, without ever giving the impression of being metal core (or death-core, as some say). The quality of the recording has improved, as is probably to be expected, and many claim the vocals are much more intense in the latest efforts than in, say, Projector. To me they sounded just fine the way they were on that record, to be honest, but it's been proven that that's absolutely just me.
Damage Done is the one you'd probably find closest to the two records you've mentioned. Character is the thrashiest and fastest of the three, sometimes criticized by its exaggerated uniformity in sound. Fiction is definitely more varied in song structure and it really harkens back to the times of The Mind's I (it's not just something reviewers write because it sounds cool).
hehe kiddin', I heard all three, with a slight preference for Character (being the one I heard the most). Not that it's perfect, by any means. I have been charmed by other bands that actually went higher on my sycophancy scale since last I came (here).