The soldier on the left of the photo is holding an M20 series “Super Bazooka” which fires a 3.5 inch HEAT round, the M28 series , with a setback armed, base detonating fuse.
The increased diameter of the warhead gives it greater penetration than the warhead of the rocket fired by the older 2.36 inch M9 series “Bazooka”. The soldier on the right of the photo is holding the older, smaller rocket launcher.
While the M20 “Super Bazooka” was designed in the closing days of WW2, it was never fielded and the smaller M9 series with 2.36 inch warhead was the American shoulder fired rocket launcher of the war. Going into the Korean War in June 1950, the US found it’s WW2 era warheads inadequate against Chinese and Korean made T-34/85s, and requests for improved rocket launchers were filled by July of that year with the first M20s arriving. Throughout the war there were several variants of the M20 made, with minor improvements to construction and increased reliability for the electrical firing system.
damn I thought that was going to be a panzershrek