Side-by-side specifications of the Synology DS414j and DS414slim, from official datasheets. Differences are highlighted.
| DS414j | DS414slim | |
| CPU | Marvell Armada XP dual-core | Marvell Armada 370 |
| Cores / threads | 2 | 1/1 |
| RAM (base) | 512 MB | 512 MB |
| RAM (max) | 512 MB | 512 MB |
| Drive bays | 4 | 4 |
| Expandable to | 0 | 0 |
| M.2 slots | 0 | 0 |
| Network | 1x Gigabit | 2x Gigabit |
| 10GbE | no | no |
| Max raw capacity | 16 TB | 6 TB |
| Hot-swap | yes | yes |
| Form factor | Desktop | 2.5-inch SATA NAS |
| Released | 2014 | 2014 |
Choose the DS414j if you want more headroom: it has a faster CPU class and a higher RAM ceiling, plus 4 bays like the slim model. The DS414slim is only worth it if you specifically need the smaller 2.5" form factor; neither has 10GbE or M.2, and neither supports expansion.