Green with no stress marks = unstressed and younger harvest, the smoother the jalap, the more mild it is
White lines begin to appear due to stress events like sun, lack of water, or simply maturing too long
Soon those white lines stretch out, and the pepper begins to change from green to orange/red. Those will be the spiciest.
So basically, jalapenos that are spoon fed are white glove, but those peppers from the hard streets that seen some **** are spicier for it