Side-by-side specifications of the Synology DS209 and DS209j, from official datasheets. Differences are highlighted.
| DS209 | DS209j | |
| CPU | 1.2 GHz | 266MHz 32-bit with floating point |
| Cores / threads | 1 core / 1 thread | 1/1 |
| RAM (base) | 256 MB | 64MB |
| RAM (max) | 256 MB | — |
| Drive bays | 2 | 2 |
| Expandable to | 0 | 0 |
| M.2 slots | 0 | 0 |
| Network | 1x Gigabit | 1x Gigabit |
| 10GbE | no | no |
| Max raw capacity | 4 TB | 4TB (2x 2TB) |
| Hot-swap | no | no |
| Form factor | desktop | Desktop |
| Released | 2009 | 2009 |
| Power consumption | 25 W / unknown | 15–36 W / unknown |
| DSM at launch | 2.2 | 2.2 |