Side-by-side specifications of the Synology DS209j and DS209+, from official datasheets. Differences are highlighted.
| DS209j | DS209+ | |
| CPU | 266MHz 32-bit with floating point | 800 MHz |
| Cores / threads | 1/1 | 1 core / 1 thread |
| RAM (base) | 64MB | 512 MB |
| RAM (max) | — | 512 MB |
| Drive bays | 2 | 2 |
| Expandable to | 0 | 0 |
| M.2 slots | 0 | 0 |
| Network | 1x Gigabit | 1× Gigabit |
| 10GbE | no | no |
| Max raw capacity | 4TB (2x 2TB) | 2 TB |
| Hot-swap | no | no |
| Form factor | Desktop | Desktop |
| Released | 2009 | 2008 |
| Power consumption | 15–36 W / unknown | 32.4 W / 18 W |
| DSM at launch | 2.2 | 2.0 |
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.