That's the complete power unit of a P-47 laid out as fitted to the fuselage - all that ducting to and from the engine, the rear-mounted turbocharger, the air-to-air intercooler and so on is why it's so bulky.
The Bf109 was the result of Willy Messerschmitt's philosophy of the bigger possible engine in the smallest, lightest airframe with the least frontal area and the tightest cowlings possible. Hence why the later 109s had to grow all sorts of bulges and fairings in their cowlings and wing surfaces to accommodate later additions of weaponry or equipment because there was so little 'spare room'. The 109 was also designed to use the minimal amount of structural elements, originally for the sake of lightness but later that proved to be highly suitable to dispersed mass production (for instance the forward wing mounting, undercarriage bracket and rear engine bearer are all combined into one single forging. But it did leave the 109 as a relatively flimsy aircraft - there was a saying in the Luftwaffe ground crews that "when an Fw190 crashes, they take the wreckage back to Focke-Wulf and Kurt Tank strengthens all the bits that broke...when a Bf109 crashes, they take it back to Messerschmitt and Willy weakens all the parts that are still intact."