By model numbers, you can follow the development of the Ruger Semiautomatic pistol. As the model numbers climb successively higher, there tends to be some engineering changes which improve upon the preceding model.
The earliest was the Ruger P85, which was developed for competition against the Beretta 92. A big, ungainy pistol, problems were found with its safety which required reengineering and a Mark II subvarient was developed (with older pistols being factory refitted). Subtle changes to the internal design led to the P89 model.
A 45 ACP version, the P91, was soon introduced, but no novel changes were made. However, about this time, a proprietary stainless was developed and Bill Ruger was so impressed that he permitted the metallurgist/engineer's name be marked on the gun (Terhune).
The P93 marked the first major change in the P series pistols. Complaints that the earlier versions were too big and bulky led to the streamlining of parts. A LE armorer, who happened to be female, walked into Bill Ruger's office and proceeded to lambast him about his pistol. He sat in silence and listened to her while the Armorer instructors trembled in silence outside ("Hw did we let her slip into Mr. Ruger's office and will we be called on the carpet for it?"). To streamline it, some parts were made multifunctional and others deleted.
The 94 continued in the evolution process and simplicity was furthered without compromising safety or reliability. Finally, the polymer linkless P95 (in 9mm) and P97 (in 45) were introduced. The P97 was not just a polymer version of the P91. Additional rails were added to the slide to ensure greater accuracy and durability. The frame was also simplified and has fewer parts than the older gun. Another major feature of the P97 was the discarding of the locking link design for a linkless lockup which worked with the guide rod.
If you can't do a side by side comparison of these guns, the next best way is to gather the parts diagrams and compare those. From those, you can see how fewer parts were used, the design simplified and streamlined.