Here's the OLED Deck specs for comparison:
APU
6 nm AMD APU
APU power: 4-15W
(which contains:)
CPU:
Zen 2 4c/8t, 2.4-3.5GHz
(up to 448 GFlops FP32)
GPU:
8 RDNA 2 CUs, 1.6GHz
(1.6 TFlops FP32)
...
RAM:
16 GB LPDDR5 on-board RAM
(6400 MT/s quad 32-bit channels)
Storage:
Steam Deck 512GB NVMe SSD
Steam Deck 1TB NVMe SSD
Both include high-speed microSD card slot
EDIT: More details
https://www.notebookcheck.net/AMD-Steam-Deck-OLED-APU-Processor-Benchmarks-and-Specs.799065.0.html
So basically, the Deck and Switch 2 are roughly inverted in compartitive hardware power... the Deck has a more powerful CPU, the Switch 2 has a more powerful GPU.
EDIT 2:
also the Deck has 33% more RAM.