Vulcans and Romulans have basically the same look (in TOS they were distinguished largely by the Romulans distinctive garb and the fact that Ronulans were only encountered on Romulan ships, in TNG and later shows the Romulans often had ridges, but not all individuals did.)

That they looked identical (except for the ridged Romulans) because of their shared origin was a quite important point from their introduction.