According to https://www.hackster.io/news/espressif-s-new-esp32-s3-adds-a... it's 512KB of SRAM on top of 384 KB of RAM.

It's also more encryption functionality, 10 more pins of I/O and retains the USB support from the S2.

I, for one, am glad I no longer have to choose between dual core and USB support.