If you look at Table 5 in your link, you'll see that not only population was growing faster in the USA, skewing headline GDP growth figures in US favor, but the employment-population ratio there was growing as well. In two major EU economies (Germany, France), it was stagnant. (It was also growing in UK and Italy at the rates resembling US ones. Overall, it seems that EU growth rates was lower). Therefore, real GDP per capita was growing faster than real GDP per employed person - which is supported by second half of Table 6. It's 1.7 in USA vs. 1.7 in France and 1.5 in Germany, a much smaller difference.

There's a related NBER Working Paper by Olivier Blanchard (March 2004). The abstract says:

After three years of near stagnation, the mood in Europe is definitely gloomy. Many doubt that the European model has a future. In this paper, I argue that things are not so bad, and there is room for optimism. Over the last thirty years, productivity growth has been much higher in Europe than in the United States. Productivity levels are roughly similar in the European Union and in the United States today. The main difference is that Europe has used some of the increase in productivity to increase leisure rather than income, while the U.S. has done the opposite. Turning to the present, a deep and wide ranging reform process is taking place. This reform process is driven by reforms in financial and product markets. Reforms in those markets are in turn putting pressure for reform in the labor market. Reform in the labor market will eventually take place, but not overnight and not without political tensions. These tensions have dominated and will continue to dominate the news; but they are a symptom of change, not a reflection of immobility.

There was some criticism levelled against Blanchard's argument that Europeans simply changed the mix of wages and leisure, because many of the changes were involuntary (on individual level). Thus, one would overestimate Europeans' welfare by assigning value equal to net-of-tax wage rate to an additional leisure hour. On the other hand, Europeans continue voting for the governments that mandate a rather short (relative to the USA) working week and working year, and so I'm not sure how involuntary it actually is in the end.