First pic, side by side

Next, stacked to see the difference in overall size:

Next, to show difference in hole size:

Difference in steel thickness:

Overall, enough difference to make it worth buying to supplement the smaller 1. The sheaths from SheathPro for the 1 work ok for the 3. I have two so I'll use the light 1 for necker and heavier 3 for belt. Perfect!