In contemporary types Didones usually have flat serifs and Bodonis usually have tapered serifs. But there are exceptions, because Bodoni’s later types are very similar to Didot family’s work.

... and there are Didones with tapered serifs too. Elder Didot is a very curious didone.

Aren’t the counters of Didots in general rounder than those of Bodonis?

I have great difficulty in recognising a didot as against a bodoni.

Why not compare the alphabets?

Didots tend to have relatively thinner hairlines.

What Nick said. Here's a starter, with the differing details that I find most striking. Always depending on the foundry/size/weight etc., of course.

F

This is almost an odd question to me, since there are relatively few Didots compared to the amount of Bodonis. Frutiger's Didot, H&FJ's Didot and Porchez's Ambroise seem to be the only actual Didots available. Canada Type has their new Didot, but it's self admittedly not a faithful Didot.

Am I completely missing out on some cool Modern types?

Dan: The Didot You Didn't Know
Plus those that have no Didot in their names, like FF Holmen or Andreu Balius’ Carmen.

Nick, I have compared quite a few bodonis with didots. I am just yet to figure
out the essence of a didot as against that of a bodoni. In many versions
the serifs of didots are very similar to a bodoni. I know the key charachter
differences, like the lowercase a and g are dead giveaways, but in capitals,
(used in magazine covers) at times I find it hard to tell if it is a bodoni
or a didot, especially when one cant really see if the serifs are flat or tapering.

Telling a Didot apart form a Bodoni is one of the few ID's I've yet to miss. Not quite sure why.

That "curve" is called bracketing. Most Didots do not have bracketing.

One definite difference I just remembered: when a hairline meets a serif (at the top of a U or W, or bottom of an A, for instance), in Bodoni it's bracketed, in Didot it's not.

wow... yes... Bodoni always is more compress and didot more relax.

On the subject of Carmen: here's a review.

>Am I completely missing out on some cool Modern types?

Dan, you're depriving a village somewhere of a didot.