Here's A
2, 4, 8, 16, 32, 64, 128, 256, 512
Here's B
20,40,60,80,100,120,140,160,180,200,220,240,260,280, 300, 320
The least positive difference appears to be 4...this occurs three times
20 - 16, 64-60 and 260-256