Howdy Bobin.
I have three '73 carbines; the oldest is a .357 that I won at a big match ten years ago. I love all of them. Obviously, the carbine action functions exactly the same as the rifles. The carbines are lighter, especially the .44 and .45 models. The .357 has enough steel in the barrel to still have some weight out front, but it may tend to wave around on you a bit if you are used to the heavier octagonal barrels. Since you are going to shoot .38's there will be some room to spare in the magazine, you might consider removing the magazine plug and inserting some heavy bullet(s), lead only of course, in the end of the tube, then replacing the plug. A couple of 250 grain .45 slugs for instance will add a bit of weight to the forward end.
Other than balance, the main difference will be the sights. The rear is not elevation-adjustable, and all of my carbines tend to shoot high. Also, the front sight is on the barrel band, so adding a bead isn't so easy. I just JB-welded a 1/8" bead (cut from brass welding rod) to the top rear of my carbine sights. It is very easy to see, but the gun still shoots high. I just aim at the bottom of the targets. There are some replacement barrel-band sights available that have a bead which is higher on the blade. And some folks cut off the blade and cut a dovetail into the top of the barrel band, or dovetail the barrel, for a marbles or other front sight with a bead. There is enough meat in the .357 barrel to do this.
Then of course there is the different buttstock. Seems like most folks actually prefer the carbine buttplate to the rifle's crescent buttplate, so you're probably okay there.
Enjoy the new carbine.