TechInsights performed a die analysis of both the A14 Bionic and the M1 Soc. As you may know, both chips are made on the same process, the TSMC N5 5nm technology. Compared with the A14, the M1 has a 37 percent larger die size.
The M1 has double as many high-performance "Firestorm" CPU cores, double the GPU cores, 50 percent larger Firestorm L2 cache, and double the DDR memory interfaces. The Icestorm CPU cores appear to be identical to the A14, with roughly the same L2 cache size. System cache is 25 percent smaller on the M1 and it has a same-size NPU as the A14.
The M1 also has some specialty blocks, that allegedly offer optimizations for desktop applications. The exact purpose of these transistors is unknown, it's part of Apple's secret sauce.