Side-by-side specifications of the Synology DS1821+ and DS2015xs, from official datasheets. Differences are highlighted.
| DS1821+ | DS2015xs | |
| CPU | AMD Ryzen V1500B 2.2 GHz | quad-core CPU |
| Cores / threads | 4 cores / 8 threads | 4 cores |
| RAM (base) | 4 GB DDR4 ECC SODIMM | 2 GB |
| RAM (max) | 32 GB | 8 GB |
| Drive bays | 8 | 8 |
| Expandable to | 10 (up to 18 with 2 DX517) | 12 |
| M.2 slots | 2 x M.2 2280 NVMe | 0 |
| Network | 4 x 1GbE RJ-45 | 2 x 10GbE SFP+; 2 x 1GbE RJ-45 |
| 10GbE | optional | yes |
| Max raw capacity | 288 TB raw with 2 DX517 | 48 TB internal; 108 TB maximum file system size |
| Hot-swap | yes | yes |
| Form factor | desktop | desktop |
| Released | 2020 | 2015 |
| Power consumption | 59.8 W / 26.18 W | — |
| DSM at launch | — | — |