They both had more and better equipment and personnel that was better trained.
For example, the Japanese had the Zero fighter airplane at a time when the United States was still using pathetically inferior planes like the Brewster Buffalo. The Germans also had good airplanes like the Messerschmitt 109 that were better than anything the US had.
In addition, both Germany and Japan had trained and battle-hardened troops where the US really did not. The US had had a very small army up until it started drafting men in 1940. The Germans had been fighting in Europe and the Japanese in China before the US got into the war. This meant that both powers had more battle-ready troops than the US did.