A photo being worth about a kiloword:
-1905 Leather sling, used on M-1903, 1903A1, M1917, and M-1 Garand rifles
Installed
Being set up
M-36 cloth sling
That M36 sling was in a middle-green color ot a faded OD. Copies have been found in a medium khaki, but no evidence of actual issue. In the 60s they were issued in black for use with the M-16. There's a spring steel clip for the rear swivel which goes to a sliding buckle, this was meant to be sized to the upper arm measurement of the shooter. So, you were to unclip the back end, fetch the loop up your ar, and tighten it all off using the forward, clamping, buckle.
A Moisin Nagant sling (if on an M-44 carbine)
Note how all the connections are leather loops.
Compare a Kar98k sling
Which actually pass thrugh the stock and buckle to a short section of leather on the right-hand side.
Above, there was mention of the 3-point slings used by some military units, a phot
Wear of different sling types
each has about as many detractors are proponents.