Side-by-side specifications of the Synology DS209j and DS209+, from official datasheets. Differences are highlighted.
| DS209j | DS209+ | |
| CPU | 266MHz 32-bit | 800MHz |
| Cores / threads | — | 1 |
| RAM (base) | 64MB | 512 MB |
| RAM (max) | 64MB | 512 MB |
| Drive bays | 2 | 2 |
| Expandable to | — | 0 |
| M.2 slots | 0 | 0 |
| Network | 1x Gigabit | 1x Gigabit |
| 10GbE | no | no |
| Max raw capacity | 4TB | 2 TB |
| Hot-swap | yes | yes |
| Form factor | desktop | desktop |
| Released | 2009 | 2009 |
Choose the DS209+ if you want the faster CPU and higher RAM ceiling; the DS209j is the slower, lower-memory option. Neither has 10GbE or M.2, and both are 2-bay units with no expansion.