Side-by-side specifications of the Synology DS1621+ and DS3615XS, from official datasheets. Differences are highlighted.
| DS1621+ | DS3615XS | |
| CPU | AMD Ryzen V1500B | Intel Core i3-4130 |
| Cores / threads | 4 | 2C/4T |
| RAM (base) | 4 GB | 4GB DDR3 ECC |
| RAM (max) | 32 GB | 32GB |
| Drive bays | 6 | 12 |
| Expandable to | 16 | 24 |
| M.2 slots | 2 | 0 |
| Network | 4x 1GbE RJ-45 | 4x1GbE |
| 10GbE | optional | optional |
| Max raw capacity | 256 TB | 216TB |
| Hot-swap | yes | yes |
| Form factor | desktop | desktop |
| Released | 2020 | 2014 |