Not sure if I have my terms right, but I'm referring to the part of the cylinder close to the forcing cone - opposite end of where you load them in. In 22lr, I see some cylinders are bored all the way through, where you can literally drop the whole cartridge to its rim on the opposite end. Then, other cylinders have a restricted end, where not even the bullet head will pass through to the case rim.
Why are some restricted and some through bored in the same caliber. Is there pros and cons to each method and what are they?

If I understand your question properly, you wonder why the charge holes at the breech end of a cylinder are larger than the holes at the barrel end.

Simply put, the center fire cartridge case is larger than the bullet and allowance must be made for that. In that instance, there is typically a shoulder in the chamber so that the bullet can be supported and guided as it leaves the cartridge case.

The .22 rimfire has the part of the bullet that rides in the grooves of the barrel outside the cartridge case, and the case and bullet are the same dimensions. The forward part of the chamber will still guide the bullet, but difference in diameter is virtually invisible.

Quality revolver chambers frequently have a slight "choke bore" at the barrel end of the cylinder. That is, the hole is smaller than nominal bullet diameter. Now then, some manufacturers have been know to save a few bucks by not going to the expense of buying chamber reamers with that feature. This is particularly true of inexpensive .22 rimfire examples.

I understand that the 22lr case and bullet are the same diameter, and that the hole in the rear (hammer side) is large enough to let the case go completely into the cylinder and seat on the case rim.
Its the hole on the other side of the cylinder (forcing cone side) I am talking about. Why do some manufacturers use a full size hole and others restrict the hole (forming a step down in diameter) to actually squeeze the bullet. I read one place that the bullet would expand in the cylinder if it was full bore diameter, and then have to shrink again when it was entering the forcing cone - so why not squeeze it in the cylinder before it enters the forcing cone. I've read else where that accuracy is improved with full size cylinder bores, bullet doing what it wants until hitting the forcing cone. What are the pros and cons of full bore vs restrictive bore?

Reread paragraph 4 of my reply. Frankly, most of the users cause far more inaccuracy than any minor machining differences. Oversize /fullsize cylinder throats tend to cause more lead spitting than ones that are restrictive.

Most of what you read is theorizing for ego enhancement.

On most modern cartridges the bullet fits inside the case so is smaller than the case diameter.As such the case being larger than the bullet the chamber to hold the case is larger but a step down in diameter(the throat) is needed to pass the smaller bullet accurately into the barrel.The .22 rim-fire has a bullet that is fit differently in the case and so is the same diameter as the case.As such there is no need for a step down in chamber diameter as the bullet and case is the same diameter.