Solving this puzzle involves finding the lines which are missing in each image.
These missing lines spell out the answer, DANCING SWANS.
*After the last puzzle of this sort I posted, which required tracing the “extra” lines in each image for extraction, I received multiple comments from people who felt that was backwards, so I switched the extraction around this time. I got just as many comments this time which prefer the other way. Next time we have a find the difference puzzle, I will be trying something completely different.