The a15 is more durable than the Snapdragon 888plus.
Apple's a series can basically be said to be two generations ahead of the Snapdragon, and the Snapdragon 888plus should be compared to the Apple a13. Even in the face of Snapdragon's latest 4-nanometer process Snapdragon 8gen1 chip, Apple's a14 actual data can be comparable.
Another point is that Samsung's 4nm process has a transistor density of 167 million \/mm, which is still backward compared to TSMC's 171 million \/mm 5nm process. Apple's A-Series, backed by TSMC, is more durable than Snapdragon.