Subaru (WRX, Forester, Liberty) and VW (Beetle, Kombi, Type 3) engines are the same basic layout and like two40 says have a different firing order to an inline 4. This is why they sound similar if you listen to exhaust noise and not mechanical noise. The VW is extra noisy because it's air cooled and does not benefit from the noise reducing properties of a liquid cooled engine.
Porsche went to a great deal of trouble on the 996 engine (1st production water cooled boxer 6 for them) to retain the "air cooled" sound.