This might not seem like a lot to us who can compare it against the extreme change that WW1 wrought on the world, but in the eyes of those who were there it would still seem like a plenty large war. It would effectively be a larger, more widespread and more deadly version of 1870 but with a reversed final result reversed. This would be a very significant event in European History, even if the Allies are able to give the Germans a bloody nose in 1914 and finish up the war in 1915/1916.
A hard fought but brief war was what was expected. The cost and size of it might have surprised people, but it was within the bounds of expectation. More significant than 1870 certainly, but not the game changer that 1914-1918 was OTL.
The big social change is that a quick war sidesteps a number of factors that resulted in major social change. For example, on the British side, you don't get the mixing of classes within the trenches. Harold MacMillan wrote in his diary at the time that he'd never before had occasion to talk to the working class, and previously, he'd assumed that they were almost a different breed of human. He wrote that he was surprised and his eyes opened to find that they were real people with real emotions and real concerns that he could identify with. This shaped his political views significantly, transforming him from an aloof Conservative to a One Nation Tory. This experience was repeated many, many times. Without it, the power structure of Britain remains on a slow change, rather than the accelerated change it got OTL.
In France, we have the Jewish experience. Previously, as the Dreyfus affair showed, conservative elements of the French hierarchy had strong anti-semitic feelings, and there was something of a view that it was almost impossible to be both Jewish and truly French. Come WWI, and the need for bodies for the Army, and Jews volunteered in their thousands, with many specifically requesting the dangerous appointment to the infantry, precisely and specifically to prove that they were both Jewish and French. That did not go unnoticed, and for a couple of decades, they made their point. (And then Vichy France came along and undid all of that, but that's a story for another day).
In Germany, you've got the factor that the Army has been outfought and there is no disguising that. No Turnip Winter, no failure of support, no slow and gentle collapse. They simply had their arses handed to them in battle, big time, and there's no-one to blame but the Army for that. Lord knows how that plays out.
In Russia, the losses of the war have been manageable and Revolution is probably staved off for a few years. Not for long, obviously. There was trouble brewing, but this will start later than OTL, and will doubtless take a different form.
Austria-Hungary retains its complicated structure, and nationalist unrest will remain a problem.
The Ottomans have stayed out of things, and French and British investment will continue apace. France had been investing heavily in what is now Lebanon, and Britain in the Gulf. This will continue and probably accelerate. Whether Germany will go with the Berlin-Baghdad railway under these conditions is a moot point.
Ireland gets Home Rule. Quite how this plays out is anybody's guess. With no Easter Rising, there is no ridiculous over-response by the British, and hence no martyrs for The Cause. There will still be problems in Ireland - that's a given regardless of how things turn out.
India is an interesting question. OTL, civil servants in the 1910-1914 era going out assumed that they would see transfer of power to Indians and Indian independence in their term of service. WWI complicated this, and most Whitehall sources suggest that it caused a delay in granting Independence. How this would have turned out, your guess is as good as mine.
The USA hasn't got involved in Europe, and probably turns its eyes towards the Pacific rather more than OTL. Quite what this means for the Britain-Japan agreement, that's right, anybody's guess. I can see America moving further down the Isolationist road, with whatever consequences that might have.
Technology hasn't had the transformation it did in OTL. On the one hand, the rapid development in aircraft hasn't happened. Which means that there is a bigger niche for airships. Not able to carry the same load as ships, but faster than ships. Not as fast as aircraft, but able to carry much more and much further. One might see development of the planned London-Sydney airship route, with several wayside stops. IIRC, Malta, Persia, India, Singapore and Sydney were the planned stations along the route, with another branch coming from Persia down to Cape Town. Developments in the cinema had been delayed by the war OTL, so we might see an earlier introduction of Talkies, and - with luck - colour.
The drive to improve production efficiency hasn't happened, so industry will remain at lower levels of production, probably giving rise to greater differentials between those countries that invest and those that don't.
Other than that, not much will change.