In this case, wikipedia is not such a good starting point, because at least the German and the French articles do not seem very well developed and are unlikely to be representative of the research in the respective countries. This is in part my subjective opinion, but can also be seen in their length, which is very short compared to the English article.
Nevertheless, there are differences between research traditions in these countries. A good introduction is Peter Warr's chapter “Some Historical Developments in I-O Psychology Outside USA" in Koppes (2007) which compares US and European approaches.
For example with regard to differences between research in the US and Germany, Warr observes that
In general, German psychologists have been more sympathetic to broad conceptual frameworks (...) This German preference is illustrated by the development of broad "action theories". Those (...)[view] the concept of action as integrating otherwise unrelated issues of job performance, stress, errors, skill development, and other processes.
Whereas American I-O psychology has focused more on abilities, motivation, and similar precursors, action theory examines knowledge, cognitive understanding, mental strategies, and processes of self-regulation. (...) This traditional focus on regulatory processes between an environmental input and behavior has been different in both style and content from most American theorizing. (p. 85).
Laura L. Koppes (Ed.). Historical Perspectives in Industrial and Organizational Psychology. Mahwah, NJ: Lawrence Erlbaum Associates, 2007.