Here are a couple of coins of Vespasian that look nothing like Vespasian. An Early portrait of Domitian as Augustus. Note the nose Here is a more idealized portrait of Domitian Here is another from a non Rome mint under Vespasian Here is one of my favourite portraits of Domitian
I agree this coin has some appealing verisimilitude. Here he is looking less beaky: Which is more accurate? Surely the really huge-nosed versions are something of a caricature. Here's a bust:
I do enjoy this rather young looking Trajan.. I do not recall seeing one like it (but I am no expert).
Some fantastic portraits all around, but how certain are we, not to mix up "realistic" and "of good style" ? Dependiing on our own taste, we can be positive about good style, while for some emperors it will be more difficult about realistic. Q
Postumus coins always surprise me with the incredibly veristic portrait but a reverse which tends to be an exercise in abstraction. Almost as if the master celator got the head while the apprentices got the reverses or something. Or maybe they wanted to have a face that looked Imperial, with a reverse that was closer to local artistic flavors and styles.
I cannot vouch for the accuracy of this portrait and it is too bad he didn't have any sestertii struck in his name however on this denarius you can sort of see his wig. ( I wonder if that was a big ooops at the mint.) Otho Ar denarius 69 AD. Obv head right bare Rv. Victory advancing left RIC 16. 3.34 grms 18 mm Photo by W. Hansen Planchet archives at: https://edmontoncoinclub.com/the-planchet/the-planchet-archived/
Your distinction is dead on. Especially as complemented by @Cucumbor's description of Postumus's portraits as 'veristic.' Across media, it's treacherously easy to mistake the esthetic appearance of verisimilitude for 'the real thing' in empirical terms.
I have a hard time coming to terms with that. Oh the one hand the images look true-to-life; on the other hand they are not realistic. I mean, Augustus was shown as a young dude even when he was an old guy!
...You can see the same kind of dynamic in all kinds of European painting and sculpture, from the period of Mannerism (late phases of the Renaissance; c. later 16th century), all the way to the cloyingly idealized 'naturalism' of of 'academic' /Salon painting of later 19th-century France, which it took the Impressionists to finally bring down.