What is the difference between the DS220+ and DS420+ models?
The main difference s between these models is
- drive bay count – RAID1 vs RAID5/6
- Warranty – 2 vs 3 years
- NVMe cache – only 4-bay has it
- Virtualizations support – only 4 bay has it
- And copy button – only 2 bay has it
Performance-wise they are very similar since they feature the same CPU, but NVMe cache do help environments with 10 or more people connecting and servers running web site or database or virtual machines.
I hope this helps.
Synology comparison bellow: