Here you see a Model 20 (1920 version) flanked by two Model 1920s (1926 version)

The barrels of all three rifles carry the patent dates March 28, 1916 - Dec 26, 1916 - June 17, 1919.
The Model 20 (center) has no model designation on the receiver or elsewhere. The receiver rings of the Model 1920 rifles (left and right) are marked "Savage 1920 Model"
The Model 20 barrel is shorter than the Model 1920 barrels.
The stocks are a little heavier on the outside rifles.
The front sight on the middle rifle is the original style. The front sight on the left rifle is the later style. The rifle on the right is a Model 1920 (1926 version) but it still has the early style front sight. Note that the front sight ramps of all three are integral with the barrel. FYI, the blade is missing from the middle rifle. I need to have it replaced.
The rifles on the left and right have two different styles of rear sight. I have seen a third style.
The rifle in the middle has a bolt mounted peep sight. These were popular with the Savage. They might be really good for a quick sight picture but the bolt moves while you press the trigger so they are not more accurate (IMO).