A38x has 32-bit ARM cores. A3720 has 64-bit A53 ARM cores. 64-bit ARM cores compared to 32-bit cores have additional instructions for crypto operations. And based on some tests it seems that some crypto done via 64-bit ARM blocks is really faster than crypto done on CESA on the same SoC. So the best is to do own tests and measure if CESA or ARM is faster. So think about it like that 64-bit ARM CPU itself has some kind of crypto accelerator engine.
