The Current Reality Tree is a sufficiency tree shows (part of) the current situation of a system. It is used to model how causes and effects lead to certain undesirable effects (UDE). The arrows in the tree show which cause leads to which effect.

When there multiple arrows from a cause to an effect, then each cause creates the effect by itself. Removing one of the causes will perhaps lessen the effect, but not remove it completely.

When the arrows are connected with a line (or ellipse sometimes) then all causes are need to cause the effect. When you remove one of the causes the effect will also be removed (and perhaps subsequent effects as well).

If an arrow points from node A to node B. You can read this as If A, then B.