Side-by-side specifications of the Synology RS3614xs+ and RS3621xs+, from official datasheets. Differences are highlighted.
| RS3614xs+ | RS3621xs+ | |
| CPU | Intel Xeon E3 quad-core 3.3 GHz | Intel Xeon D-1541 |
| Cores / threads | 4 cores / 8 threads | 8 cores / 16 threads |
| RAM (base) | 8 GB ECC | 8 GB DDR4 ECC UDIMM |
| RAM (max) | 32 GB ECC | 64 GB |
| Drive bays | 12 | 12 |
| Expandable to | 24 (up to 36 total) | 36 |
| M.2 slots | 0 | 0 (via PCIe adapter cards) |
| Network | 4 x Gigabit | 4×1GbE RJ-45, 2×10GbE RJ-45 |
| 10GbE | optional | yes |
| Max raw capacity | 216 TB | 1 PB single volume |
| Hot-swap | yes | yes |
| Form factor | 2U rackmount | 2U rackmount |
| Released | 2014 | 2021 |
| Power consumption | unknown | — |
| DSM at launch | — | — |