Is there a difference between nationalism and the fact that Italy does in fact has almost twice as high of a corruption index as Germany or that Spain has half the GDP?
Comparing the GDPs of two countries and assuming the difference must be due to laziness is almost the epitome of prejudice.
the difference is knowing a statistic and generalizing it to each and every citizen of a country. Especially the "lazy" part - that has even been proven to be completely untrue if you look at hours worked etc.