[Martee]

in reality, about how far apart are the impact plane line and the low point plane line usually?...also is the sweetspot plane line between them?

-hcw

Starting with the ball located at Low Point, all three of these lines will appear as one. The further back the ball is located from Low Point, the wider the separation becomes between the lines. So the distance of separation is variable for a single club by ball location to low point. The distance is also different between clubs.

Yes the Sweet Spot Plane Line is inbetween them.

Diagram 2-C-1#1 gives a good view of this from down the line.