Side-by-side specifications of the Synology DS409slim and DS420j, from official datasheets. Differences are highlighted.
| DS409slim | DS420j | |
| CPU | 1.2GHz | Realtek RTD1296 |
| Cores / threads | — | 4-core |
| RAM (base) | 128MB | 1 GB DDR4 |
| RAM (max) | 128MB | 1 GB |
| Drive bays | 4 | 4 |
| Expandable to | 0 | 0 |
| M.2 slots | 0 | 0 |
| Network | 1x Gigabit | 1 x 1GbE RJ-45 |
| 10GbE | no | no |
| Max raw capacity | 3TB | 64 TB |
| Hot-swap | yes | no |
| Form factor | 2.5" NAS | desktop |
| Released | 2010 | 2023 |