The armies involved were much smaller, the territory being covered much larger, and the belligerents much poorer and less technologically-sophisticated.

For one, this means far less field artillery. The popular image of the 1914 fighting is of men being mowed-down by new-fangled machine guns and forced to scrabble into trenches. But artillery was probably the biggest cause of the heavy casualties in the maneuver warfare on 1914 that preceded the trench stalemate of 1915 (250,000 casualties in the six days of 1st Marne in Sept 1914). Before the war, all the belliegrents had heavily-invested in developing light, rapid-firing field artillery. This took an enormous commitment of industrial resources to build guns and supply them with ammo. It took an enormous commitment of manpower and horseflesh. In 1914, a Royal Horse Artillery battery with six 13-pounder guns needed 205 soldiers and 228 horses.[1] Those gunners and horses took months, or even years of expensive training to master the difficult art and science of fighting their guns. And of course, all this cost huge amounts of money.

The belligerents in the Mexican revolution absolutely used artillery, but never in the large-scale systematic way as the great powers of Europe. They didn't have the horses, the industry, or the money to field massed field artillery. Fewer guns reduces one of the strongest forces that pushed armies into trench fighting.

To give you an idea of the destructive firepower at play, here's an interesting comparison of the British Ordnance QF 18-pounder and the German 7.7cm Feldkanon 96 howitzer. https://m.youtube.com/watch?v=Di5svup9BkY

Two, it means fewer machine guns. Early machine guns (mostly Gatlings, Lewis Guns, Maxims, Hotchkisses, and Colt "potato diggers") were expensive, complicated machines. In the early 1900s, a Maxim gun cost about $25,000-30,000 in today's money. [2] And that wasn't counting the cost of the tripod or carriage, which could cost another $3,000-4,000. Add on the massive ammo expenditures of a machinegun in action and machine guns become unaffordable for a poor army to field in large numbers. Furthermore, the US refused to sell guns to groups like the Zapatistas, forcing them to rely on stolen guns or guns bought at a premium on the black market.[3]

Three, industrial-scale chemical warfare was still in it's infancy by the start of the Mexican revolution. The idea of chlorine-filled artillery shells went back to the American Civil War (they were never built or used) and the Hague Declaration of 1899 and the Hague Convention of 1907 had both banned the use of "poison" weapons. But chemical weapons hadn't been refined and perfected by 1913. It took the cooperation of German chemical giants like Bayer and scientists like Fritz Haber to refine and produce hundreds of tons needed for the first chemical attacks in 1915. War-torn Mexico simply didn't have the industrial or scientific capacity to seriously develop chemical weapons or their own, or even to use pre-war weapons like tear gas.

As for aircraft, the Mexican Revolution was actually a sign of things to come. Both sides bought small numbers of aircraft (mostly Wright or Curtiss "pusher" biplanes) and hired Mexican and foreign pilots to fly them. They were used for recon missions. In April 1914, Constitutionalist pilot Gustavo Salinas Camiña dropped several bombs on the Heurtaist gunboats Guerrero and Morelos. The bombs all missed, but it's widely-regarded today as the first aerial bombing of a warship. The Revolution also lead to the first aerial duel. In November 1913, American mercenaries Dean Ivan Lamb and Phil Haber blazed away at each other with pistols (neither of them hit).[4]

[1] https://www.forces-war-records.co.uk/units/4670/royal-horse-and-field-artillery

[2] https://www.forgottenweapons.com/the-world-standard-maxim-gun/

[3] http://www.smallarmsreview.com/display.article.cfm?idarticles=286

[4] https://www.google.co.kr/amp/s/firstinaviation.wordpress.com/2017/04/18/dean-ivan-lamb-and-phil-rader-first-dogfight/amp/