Human expansion to the galaxy was the final frontier war. Data channels back from the field of war mostly nonexistent. The war was fought from extreme distances with adaptive weapons. The actual events of the battlefield itself were not important for strategic point of view, but of course topic of speculation and interest. How we picture these events tells us something about ourselves.
The wars against unknown and alien enemies had to be sold to Earth population. After the victory in the Klendathu system the interest toward the war started to decline. Earth scored victories in its own light cone, and it was becoming clear that there is match for human faster than light technology.
Starship Troopers is an example of propaganda made during the final decades of the war. It is set in the time when the border skirmishes escalated to full scale expansion war after an attack to Earth itself. The focus is on human return to Klendathu system and the first decisive human victory on the system: the capture of enemy control node at Klendathu planet P.
In warfare against organized enemy the primary targets are the command structure, communications facilities, and logistics centers; that is the ability of the enemy to fight the war. Of course, it was not known if the lessons learned during millenniums of human warfare would work against alien adversaries. They did; especially so in the Klendathu system.
The predictive algorithms of the pre-strike scanner probes entering the Klendathu system isolated the enemy decision making entities, in military terms "control nodes", and launched exploratory attacks on their physical locations. The enemy was defending these nodes fiercely, and as one was finally captured or destroyed, the enemy efforts were hugely diminished.
In Starship Troopers, the enemy themselves are shown as huge and powerful versions of insects of Earth. The physically superior aliens without technology is based on the real underestimation of the opposition in Klendathi. Initially the probes did not detect anything comparable to human technology. This lead to the underestimation of the enemy and defeat on the first assault to the Klendathu system. This event is depicted in Starship Troopers quite amusingly with bombardier beetles knocking down starships from orbit.
The control node is depicted in Starship Troopers as a "brain bug", controlling the other enemy critters. This was actually one of the leading war-time theories for the actual meaning and form of the control nodes; along with other theories based on hive minds. It is even possible that humans actually contacted the alien intelligence of the control node during the victory on the Klendathu-P. All information about those are of course highly classified military secrets.
Let us contrast the war-era propaganda of Starship Troopers with another source depiction of Klendathu-P. Avatar is production of independent Klendathu, full of hatred toward Earth and former colonial past.
Avatar is set on the first mining colony in Klendathu-P. The failure pre-FTL-era colony was one of the big mysteries of its time and along with other border conflicts led to the militarization of Earth. The plot generator has obviously data mined colonial stories of Earth's past, and drawing from multiple rumors and fringe theories. The potential sabotage from the xenobiology research unit has been considered by even credible historians, though. But our focus here is the depiction of the aliens.
In Avatar, the primary alien intelligence is, anthropomorphically, humanoid population. The control node is assumed to be a communications and data storage; depicted as a sacred burial ground. The ancestors talking in the control node are of course reference to current practice of uploading human minds, further suggesting similarity between the aliens and the humans.
Avatar also draws from the rumored black ops program, which according to the conspiracy theorists aimed to infiltrate enemy through human controlled alien bodies. This is a weird choice (though required by the plot), as this theory is usually linked with the "brain bug" hypothesis of the Troopers. The supposed mechanism of this infiltration is the hijacking the command channel between the "brain bug" style central intelligence and the controlled alien drone.
Otherwise the depiction in the sources are similar. Alien victories despite the lack of human technology equivalents is shown as huge and physically strong aliens. Also the notion of colonists fighting against the whole ecosystem of the planet is there.
Also the human contact with the alien control node differs mostly in the mood of the story. In Avatar, the human characters making contact with the node leave their humanity behind (one dying, one becoming alien himself). In Starship Troopers, the human characters meeting the brain bug have their brains eaten.
The history is written for the victors.