Threre isn't huge difference
well it depends , i bought it cause i always wanna max from the hardware.
The 27W charger charges my phone from 5 to 62% in 30mins and
5 to 93% in 1Hr.
charged 18 to 100% in 1Hr 10mins.
While in Stock 18W charger it charges 5 to 46% in 30mins so difference...