However, upon closer inspection there are two significant differences. The coin seems to me to be made of copper rather than billon. The coat of arms also clearly differs from the picture used at KM 196.
I don't have a definitive answer, but many billion coins have very little silver and coins of that era often have significant die variations, especially from year to year.
Sorry for my ‘very last’ 😉 question, but actually I don't understand why you say this isn't a variant? Surely there is a significant difference, like the Roman numeral "I" with a modern "1"?
We all know coins where you need a magnifying glass to see the difference between the 'original' coin and his variant(s)?
Varieties refers to differences in coins of the same year (differences in one die from another). Many times the variants are listed with separate year lines (for the same year). This would be a change in the design. Usually this type of difference is given a different catalog number but obviously not always.