Side-by-side specifications of the Synology DS1513+ and DS1515, from official datasheets. Differences are highlighted.
| DS1513+ | DS1515 | |
| CPU | Intel Atom Dual Core 2.13 GHz | Annapurna Labs Alpine AL-514 |
| Cores / threads | 2 cores / 2 threads | 4 cores / 4 threads |
| RAM (base) | 2 GB DDR3 | 2 GB |
| RAM (max) | 4 GB | 2 GB |
| Drive bays | 5 | 5 |
| Expandable to | 10 (2× DX513) | 15 |
| M.2 slots | 0 | 0 |
| Network | 4× Gigabit | 4 x 1GbE |
| 10GbE | no | no |
| Max raw capacity | 60 TB with 2× DX513 | 40 TB |
| Hot-swap | yes | yes |
| Form factor | Desktop | Desktop |
| Released | 2013 | 2015 |
| Power consumption | 51 W / unknown | — |
| DSM at launch | — | — |
Choose the DS1515 if you want the newer, faster platform: it has a quad-core Atom CPU and support for 10GbE via expansion, while the DS1513+ is an older dual-core model with more modest networking options. The DS1513+ tops out lower on RAM, while the DS1515 can take more memory; both are 5-bay units, but only the DS1515 class supports Synology’s newer expansion and M.2-era ecosystem. If you don’t need the newer CPU and upgrade path, the DS1513+ is the cheaper, simpler buy.