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 | quad-core CPU |
| Cores / threads | 2/2 | 4 |
| RAM (base) | 2 GB | 2GB |
| RAM (max) | 4 GB | 6GB |
| Drive bays | 5 | 5 |
| Expandable to | 10 | 15 |
| M.2 slots | 0 | 0 |
| Network | 4x Gigabit | 4x 1GbE |
| 10GbE | no | no |
| Max raw capacity | 60 TB | 40TB |
| Hot-swap | yes | yes |
| Form factor | desktop | desktop |
| Released | 2013 | 2015 |
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.