Net gives an idea about connectivity in a circuit. Scheme-it can:
Clicking a wire will select the whole net.
If you want to select a single wire of a net, click the wire again after selecting the net. Or, hold Ctrl while clicking a wire.
It's possible to show net label on the schematic. In cases where the net consists of many wires and they are scattered, the label will appear at center of all wires.
Certain kinds of wiring might be unsafe.
Make the wise choice.
Color, line style and net name can be changed.
Color, line style of a single wire can be changed as well, if you really need to.