Question

------ image means merging all the layer into one​

Answer 1

Answer:

summary, the only substantial ways in which the two functions differ is that flattening the image will merge all the layers into one background layer whilst merging layers will only combine the selected layers, and the Merge Layers function preserves transparency whilst the Flatten Image function does not.

Answer 2

Answer:

flatten image means merging all the layer into one.