Not sure what exactly OP had in mind, but it certainly better illustrates structural differences between the countries, as well as oddities within the countries.

People already explained why Galicia in northwestern Spain looks so different (the settlements are smaller, making the population more spread out), but there are also details in other countries that make me curious. For example why Saxony has such a noticeably denser network than the rest of eastern Germany (with the exception of Berlin, of course).