I deliberately made the heads the same size for the sake of proportionality. Note that Jack White used the newspaper like a ruler and determined that the height of the man on the left was only 5'6". Oswald was 5'9", and he does look to be taller than the other man.
But, what about their builds?
I would say that the guy on the left looks stockier and more athletic, like he played more sports in his life. He had a more athletic build than Oswald had then or ever had. He had a more v-shaped build, with wide shoulders and narrow waist.
What about their hands?
I would say that the man in the Backyard photo had a heavier hand with larger knuckles and wider, chunkier fingers. Oswald's hands were more delicate. Oswald also did not have that bump on his wrist seen in the Backyard photo, also first noticed by Jack White.
What about the dark pull-over sport shirt seen in the Backyard photo? If he had it in April, he should have had it in November. Was it among his clothes? They never showcased it, did they? So, what happened to it? It doesn't look tattered or threadbare in April, so he should have had it in November. The same applies to the pants. The whole outfit should have been found among his possessions.
What about the watch? Are there any other images of Oswald wearing that watch?
There better be other images of him wearing that watch and wearing it that way, with the face out. I wear my watch opposite to that: with the face on the inside, and for two reasons: 1) it's easier and more comfortable to externally rotate your wrist than to internally rotate it, and 2) you're less likely to damage the watch. But, if Oswald wore it as seen in the Backyard photo, fine, but let's see the other pictures because it can't be that that's the only time he wore it that way. Watch-wearing is a very consistent habit, including how you wear it.
Another problem is that Oswald wore his ID bracelet on that wrist.
That's the same wrist, his left wrist. So, if he had the habit of wearing his ID bracelet on that wrist, don't tell me he also wore a watch there. On the same wrist? Why do that? And it was a pretty bulky bracelet.
Anyway, where's the watch? It had to be among his possessions. Don't tell me he lost it.
What about the thickness of the necks?
That's not Oswald's neck on the left. It's too brawny.
Folks, that guy on the left is not Oswald. He is a different man. It is a phony photo in which the core of Oswald's face was pasted on to the body of another man. Not the whole head, and not even the whole face. As Jack White said, Oswald did not have an anvil-like chin as seen in the Backyard photos. They left the other guy's chin in to reduce the conspicuousness of the paste-up job.
This was a photographic alteration that was done BEFORE the assassination. Now, if they had the mindset to alter photos BEFORE the assassination, don't you think they were prepared to do it AFTER the assassination?