The French originally issued the Lebel, made in 1886. It fired 8mm bullets. The Lebel's magazine was loaded eight cartridges horizontally instead of vertically and was placed under the barrel. This meant that that front of one bullet could hit back of the bullet in front of it, causing small explosion. This could be avoided if the riflemen loaded slowly, but that just caused more problems.
In 1916, the Berthier was issued. The Berthier was more up to date like the other rifles of the time. It was vertically clip loaded and was a bolt action. The original Berthier only had three round clips, but the one issued in 1916 had six.
The Austria Hungarian rifle of choice was the Steyr-Mannlicher 1895, designed in 1895 by Ferdinand Ritter Von Mannlicher. Unlike the other bolt action rifles in this era, it was a straight-pull back instead of a rotating bolt action. It fired 8mm bullets and could fire 35 rounds a minute, which is a lot for this time in history.
The American M1903 Springfield is a bolt action, 5 round clip loaded rifle.
But when America entered the war, there was a shortage of M1903 Springfield rifles, so instead of resetting the factories to produce Springfields, they adapted the British Enfield to for American cartridges. The magazine, rifling dimensions, chamber and bolt face were altered and the sights adjusted. And thus, the M1917 Enfield was born. The M1917 Enfield was much better than the Springfield and most of the troops were issued an Enfield.