Side-by-side specifications of the Synology DS119j and DS120J, from official datasheets. Differences are highlighted.
| DS119j | DS120J | |
| CPU | Marvell Armada 3700 88F3720 | Marvell Armada 3700 88F3720 |
| Cores / threads | 2-core | 2-core |
| RAM (base) | 256 MB | 512 MB |
| RAM (max) | 256 MB | 512 MB |
| Drive bays | 1 | 1 |
| Expandable to | 0 | 0 |
| M.2 slots | 0 | 0 |
| Network | 1x 1GbE RJ-45 | 1x 1GbE RJ-45 |
| 10GbE | no | no |
| Max raw capacity | 12TB raw / 108TB volume | 16TB |
| Hot-swap | no | no |
| Form factor | desktop | desktop |
| Released | 2019 | 2024 |
Pick the DS120J if you want a newer 2-bay unit with a faster CPU and better upgrade headroom: it has 512 MB RAM versus 256 MB on the DS119j, and one extra bay for RAID/expansion flexibility. Neither model has 10GbE or M.2, so those aren’t deciding factors here. The DS119j is only worth it if you’re getting it significantly cheaper and can live with a single bay and lower RAM ceiling.