connect

Two forms. connect R1 1 U2 7 puts R1.1 on whatever net U2.7 is on; connect R1 1 VBUS names the net instead. The difference from draw_wire is the TARGET: draw_wire goes to U2.7 itself, connect goes to the nearest point of its net, which is often a short stub beside R1 rather than a wire across the sheet. Nearest means nearest by the route, not in a straight line.

Already connected is success and draws nothing, so re-issuing it is safe. A name that matches more than one net is REFUSED with the members of each, because guessing there produces a plausible wrong netlist — run nets to see which names are safe. A route that would also join a third net is refused too, and nothing is drawn.

A POWER net — one driven by a power symbol or an implicit power pin — gets a power symbol placed beside the pin instead of a wire across the sheet, which is the KiCad idiom and keeps the sheet routable for the next connection. The result says so, and names what it placed. A net merely NAMED "GND" but drawn as an ordinary rail is not a power net, and is wired normally.

Also refused at either end: a HIDDEN pin, which has no terminal on the sheet to wire to (a hidden supply pin already joins by its name — target that name instead), and a pin carrying a no-connect marker, which says it is meant to stay unconnected.