Switching to push-feed was the most visible difference, so that is what most people key in on, but there were other differences: elimination of the claw extractor, use of painted aluminum in non-critical parts, lots of stamped metal parts, and use of streamlined manufacturing that degraded and devalued the higher end guns by producing low-value "bargain" guns on the same line in order to try to gain economies of scale. The lack of the claw extractor was the least of the issues.
In some ways, the post-64 rifles were an improvement over the pre-64s: better wood and wood finishes, better checkering, better barrels, etc. But there were many issues with the first series off the line, so the bad taste stuck.