Side-by-side specifications of the Synology DS418 and DS418j, from official datasheets. Differences are highlighted.
| DS418 | DS418j | |
| CPU | Realtek RTD1296 | Realtek RTD1293 |
| Cores / threads | 4-core | 2-core |
| RAM (base) | 2 GB DDR4 | 1 GB DDR4 |
| RAM (max) | 2 GB | 1 GB |
| Drive bays | 4 | 4 |
| Expandable to | 0 | 0 |
| M.2 slots | 0 | 0 |
| Network | 2x 1GbE | 1x 1GbE RJ-45 |
| 10GbE | no | no |
| Max raw capacity | 40 TB | 40 TB raw |
| Hot-swap | yes | no |
| Form factor | desktop | desktop |
| Released | 2017 | 2018 |
Pick the DS418 if you want the more capable box: it has a faster Intel CPU, 2 GB RAM, and supports up to 6 GB total, while the DS418j uses a slower ARM CPU and only 1 GB RAM. Neither has 10GbE or M.2, and both are 4-bay units with no expansion bays.