The 12496 is a Philips/Osram part number designating a halogen bulb for specialty applications, rated at 12 volts.
The PY21W follows the ECE standard used in Europe and worldwide markets, featuring a single filament, amber glass, a BAU15s bayonet base, and a 12-volt, 21-watt rating.
The BAU15s base on the PY21W has an offset pin arrangement, which prevents it from being seated in sockets designed for the more common BA15s straight-pin base.
For the Daewoo Lanos front turn signal, the 2000 model year uses a PY21W, while the 1999, 2001, and 2002 model years use a 12496.
The rear turn signal position shows a reversed pattern, with the 2001 model year using a PY21W and the 1999, 2000, and 2002 model years using a 12496.
The 12496 and PY21W are not directly interchangeable despite sharing a 12-volt operating voltage, as they differ in wattage rating, base type, and glass color specification.
The PY21W designation encodes its key electrical characteristics, with "P" indicating a single-filament construction, "Y" denoting amber coloring, and "21W" specifying the wattage.
No single bulb type is used consistently across both the front and rear turn signal positions for any given model year of the Lanos.