Side-by-side specifications of the Synology DS1515 and DS1520+, from official datasheets. Differences are highlighted.
| DS1515 | DS1520+ | |
| CPU | quad-core CPU | Intel Celeron J4125 |
| Cores / threads | 4 | 4-core |
| RAM (base) | 2GB | 8 GB |
| RAM (max) | 6GB | 8 GB |
| Drive bays | 5 | 5 |
| Expandable to | 15 | 15 |
| M.2 slots | 0 | 2 |
| Network | 4x 1GbE | 4 x 1GbE RJ-45 |
| 10GbE | no | no |
| Max raw capacity | 40TB | 80 TB |
| Hot-swap | yes | yes |
| Form factor | desktop | desktop |
| Released | 2015 | 2022 |