XRAY - Model racing cars

Page 32 of the Hudy Setup guide states the following, and the diagram on the same page illustrates this:

Line ‘A’ is parallel to the upper suspension arm.
• Line ‘B’ is parallel to the lower suspension arm.
• Line ‘A’ and line ‘B’ intersect at point ‘IC’ (instant center).
• Line ‘C’ goes from the wheel contact point (WC – bottom center of the wheel) to point IC.
• The point at which line ‘C’ crosses the car’s centerline (CL) is the roll center.

But when I go to page 34 it shows two diagrams, the lower has the roll center shown going through line "B", contrary to what is stated above. Using the above steps, it looks as though the roll center actually changes by only a couple mm.

Am I reading this wrong?

You are correct, the roll center should be on the C-line in the bottom picture too. Looking at the correct position the difference between the two settings appears small. However in the top picture the B-line shown is actually not parallel to the lower arm. Looking at the correct angle you will see that the difference in roll center between both pictures is actually reasonably large. Also note that even a few mm difference in roll center has a big effect on the track.