Difference Between Special Image and Normal Image

What is the difference between the Special Image and Normal Image when flashing OS?

Can you explain what guide you are following?

There is no Special Image in the 96Boards documentation for this board:

Oh the one I’ve downloaded under Images of mediatek-x20-aosp 16.10 it comes with 2 Image, the Normal and the Special Image.

It really would help if you could provide real hyperlinks to guides and what you download otherwise I have to guess which document you are reading and what you are downloading.

However… I did make a guess from the partial filename you shared and think I have an answer. See:
http://releases.linaro.org/96boards/helio-x20/mediatek/aosp/latest