The IOPS for a typical hard drive is about 300-500. Conversely for an SSD its 10s of thousands. Writes may be constrained to under 50000 while reads may generally be closer to 100000. Thats like a 100x difference.

These numbers will vary by individual device comparison but suffice to say the SSD is going to be substantially faster for reads and writes.

The Bitcoin IBD sync and verification will perform lots of reads and writes. On a raspberry pi 4 sync on an SSD may be about 5 days. On a hard drive, id guess 3-4 months. CPU is also a bottleneck, so if on a beefier refurbushed PC or NUC, the initial IBD and sync may be 1-2 days.