JIM 117 strikes me as more of a generic war cover and is from '65 when Vietnam was escalating from an occupation to a response to an "attack on the US", at least in the public's eye. Public perception would be, "Hey, Thor's helping the troops!" It's cartoony to the point of silliness (the guy with the mortar is dropping the round in backward...)
Cap 125 is 5 years later, more gritty, and now well into the era of protest against the war. This is post-Tet, Nixon is in office, and the US public wants us out. The art is much starker and realistic, to the point of almost being subversive when you consider the fact that it's Captain freaking America about to get stabbed in the back!