I was wondering how the industries and economies of both countries differed from one another. I know that the USA had great influence on them and some even say Japan and Germany were Americanized. What were the most important features of the miracles and what were the greatest similarities/difference?
In theoretical terms, the Japanese and German economic miracles were identical. Primarily because they were the main case studies for growth economists who were inventing new models at the time. The most famous of these is the Solow model, which holds that all countries with the same savings rates, depreciation rates, technological growth rates and population growth rates should converge to the same incomes. A corollary of this is that any reasonably advanced country whose capital stock was completely destroyed by the war should grow much faster than one which wasn't. In fact, it can be demonstrated mathematically that growth was a function of distance from the steady state capital stock. In that sense, Germany and Japan's extremely quick growth was simply par for the course, once the Allies reversed their positions on obliterating the German and Japanese economies.
In terms of specifics, the drivers of growth differed quite significantly. Germany had significantly less problems to deal with, since its primary pre-war export market - Western Europe, was essentially intact. Japan's primary pre-war market however, was China, which accounted for 40% of trade in 1930. Problematically, China went straight into civil war and by 1949 had become Communist. On the cusp of economic disintegration, Dean Acheson decided that a strong Japan was better to preserving American influence in Asia than a weak Japan and offered preferential access to the American market to compensate.
Japan also had perenial food security issues, which Germany did not have because it was surrounded by large agricultural neighbours. Japan had never been a truly agricultural nation, and in the past 150 years had been running a permanent rice trade deficit. In 1940, 75% of all rice consumed in Japan came from Korea, and 80% of all sugar consumed in Japan came from Taiwan. With the disintegration of their colonial empire, Japan had to give birth to a domestic agricultural industry on sub-par soil quality, and fast, since the country faced constant famine until 1952.