Any difference between these two option commands? Which one do you prefer?
Also, for scale, I can change the centimeters. What's the meaning of width=1\textwidth?
width means an absolute width of the image in the document. \textwidth is the value of the width of the text body, from left to right. So, no matter what resolution or width the image actually has, this command scales it so it matches the text from left to right margin.
scale=0.5 means scaling by a factor, here it's 50 percent, the half. It's relative to the image original size: if it's 10cm, it now becomes 5cm. So scale is less often used, since it's a multiple (fraction) of the image dimension, not the text dimension.