How did technology make world war's different from earlier wars?

Answer 1

airplanes were the most different.

Answer 2

While this is a very broad question, an example would be that of the use of hot air balloons and aeroplanes in the First World War.

The British Royal Flying Corps began to use these methods to map the trenches of the German opposition and form appropriate battle plans, and later on the pilots would drop hand-held explosives from their planes on the trenches, in the first application of a bombing run.

Another example would be that of the tank. When it was originally invented (designed by Royal Naval engineers of all things) the tank was the new offensive weapon for the British. The Little Willie, as it was called, was shaped in such a way that it could easily traverse the crater-strewn no-man's-land between the trenches, and the Germans had never seen a weapon of this type before, greatly effecting morale.

If you're looking for a more broad answer, not only on the First World War, it may be worth you reading On War by Carl von Clauswitz. Otherwise, it may be worth you making your question a little more specific.