Warfare changed in many very important ways over this time. Let us look at two of them.
Technologically, warfare became much more mechanized and industrial over this time. At the beginning of the time period, there were no machine guns or tanks or airplanes. By the end of the period, these sorts of weapons decided WWII.
Socially, warfare changed because of this mechanization. The idea of "total war" came to the fore. The people who produced the weapons came to be targets for attack even though they were civilians. The whole of a society also had to be engaged in the war effort so as to produce the huge amounts of materiel needed to fight.
tanks were introduced a little bit after WW1 and for WW1 they used trenches as a war mechanism and other little tools like shovels etc when the invaders went in the trenches. Then in WW2 they used more tanks and airplanes like germany they were the ones who usually used more of the new technologies for war