In my opinion, as someone who does *not* think that they have aphantasia, the two things are definitely not equivalent. I know what the afterimage is, I know what it is to visualize something, and they are completely different both qualitatively and intellectually.
But as I keep saying, there are people on this thread that are saying they are literally equivalent. I don't know if I believe them, but that is what they are saying -- talk to them!