The top gun is an early post-war K22 Masterpiece. It has the new "speed hammer" also called the fishhook hammer by some collectors. The term refers to the shape of the hammer tang which I think looks more like a tomcat's tail than a fishhook. The bottom gun is a pre-war K22 Outdoorsman's revolver, AKA the 1st Model K22. It was made from 1931 to 1940. In 1940, S&W introduced the K22 Masterpiece with a short throw action and microclick adjustable rear sight but no top rib on the barrel. This model is referred to as the K22/40 by collectors. It was only made for a short time and is highly collectible.
Here is my K22 Outdoorsman.