Everything means something; usually more than just one thing. Archaeological maps are no different.
The first map presents a distribution of enclosures in Europe. That map has been published several times by several authors for a long period of time. In that map Iberia is almost a desert and that has at least two readings.
Both are expressed by the second map. Iberia has also a lot of enclosures, not just walled, but also ditched. This is a result of recent work that is demonstrating that Iberia is participating of the structural trends of Recent Prehistoric Europe (I wonder why is there some surprise). But what these maps also show is the low level of internationalization of Portuguese archaeology. If there isn’t a significant effort of European researchers to get acquaintance whit Portuguese archaeology (and language doesn’t explain it all), it is also true that Portuguese archaeology has lower levels of internationalization (and language is still not an excuse). New data is available for some time now and it is not reflect in recent international publications.
So what do those maps really express? The desert on Portugal ravels, in a way, the recent nature of the developments of Portuguese Archaeology (the recent discovery of several ditched and walled enclosures) but also reflects its traditional poor conditions for international relationships and circulation of information.
So those distribution maps need a careful hermeneutic approach. As usually happens whit any kind of statement.