Over the last 20 years OECD countries have converged in terms of their innovation, in parallel to the process of economic convergence and catching-up in technology. However, this has not led to a similarity in the sectoral strenghts of the majority of countries. Applying a measure of "technological distance" between pairs of countries based on patents, it is shown that nations have increased their technological specialization (i.e their sectoral differences) over the 1980s. An apparent paradox is pointed out, as countries converge by becoming more different and grow by becoming more specialized.