Coil 1:
22 × 12 × 0.87 mm, 27.9 μH, 1.21 Ω
Coil 2:
30 × 10 × 0.52 mm, 12.8 μH, 1.27 Ω
The specification sheets for both says they are rated for 2 W maximum.
Now that got me confused. If both are 2 W maximum, then what difference does the size and inductance make? Which one is better to choose and why?
The coils are typically used in a resonant circuit for maximum power transfer. The inductance of a given coil will influence the tank capacitor selection; the datasheet for whichever wireless charge controller you're using will give you detailed information on sizing these components. There should also be some consideration given to coil size in relation to the transmitting coil for maximum coupling. Aside from that, the powers and resistances are the same so whichever coil physically fits into your system is the "better" one.
