Difference of typical lighting system wiring connections

1.  Common Low Voltage (240V a.c. 50Hz) and Extra Low Voltage (12V a.c. 50Hz)

No polarization required  (equivalent to parallel connection)

2.  Constant Current Driver (power supply)

Typical for 350mA and 700mA LED lighting
Serial Connection (polarization required) must be RED(+) connected to BLACK(-) and BLACK(-) to RED(+)

3.  DC12V and DC24V Constant Voltage Driver (power supply)

Typical for LED Strip or Rope Lighting (i.e. LED Twister, Snake, Rule etc).
Parallel Connection (polarization required) all RED(+) wires connected together and BLACK(-) wires  with BLACK wires together