Thank you all for responding. Yes, I had seen the summary table at the bottom of Colt's web page. I did a screen capture of all the 5" barrel models and put the tables side by side so I could compare one model with another. It was when I did that exercise that I realized I didn't understand the importance of some of the characteristics, and therefore couldn't figure out the differences. I've attached those three files to this post.
Near as I can tell there are three major differences between these categories: price, options, and fitment. Price and options are self evident. Fitment is the matching of components so as to ensure the best fit. The same manufacturing processes occur in both categories, but the highest quality results are separated out from the yield and put into the high end guns.
The book has also helped me understand that the low end guns are not bad guns at all. The casting process can make a very good gun even though it will not have the lifetime durability of a forged gun. He actually speaks well of the filipino guns as good first owner pistols.