変更点は
1GbE→2.5GbE
eSATA→USB-C

くらいかな？

DESKTOP SOLUTIONS
DS1825+ – AMD V1500B, 2.5GbE ×2
DS1525+ – AMD V1500B, 2.5GbE ×2
DS925+ – AMD V1500B, 2.5GbE ×2
DS725+ – AMD R1600, 2.5GbE ×1
DS625slim – Intel J4125, 2.5GbE ×1
DS425+ – Intel J4125, 2.5GbE ×1
DS225+ – Intel J4125, 2.5GbE ×1
DS1825xs+ – AMD V1500B, 2.5GbE, 10GbE + OOB

s://nascompares.com/news/synology-ds525-ds1525-ds425-ds1825-and-more-revealed/