Side-by-side specifications of the Synology DS1515 and DS1520+, from official datasheets. Differences are highlighted.
| DS1515 | DS1520+ | |
| CPU | Annapurna Labs Alpine AL-514 | Intel Celeron J4125 |
| Cores / threads | 4 cores / 4 threads | 4 cores / 4 threads |
| RAM (base) | 2 GB | 8 GB DDR4 non-ECC |
| RAM (max) | 2 GB | 8 GB |
| Drive bays | 5 | 5 |
| Expandable to | 15 | 15 total (2 DX517) |
| M.2 slots | 0 | 2 NVMe M.2 2280 |
| Network | 4 x 1GbE | 4 x 1GbE RJ-45 |
| 10GbE | no | no |
| Max raw capacity | 40 TB | 80 TB internal raw; 108 TB maximum single volume |
| Hot-swap | yes | yes |
| Form factor | Desktop | Desktop |
| Released | 2015 | 2020 |
| Power consumption | — | 52.06 W / 16.07 W |
| DSM at launch | — | 7.0 |