Your rifle has the volley sight mounts and most probably a stock disk plug which were never on the 1917 Rifle so the stock at least is a P14 (Pattern 14). The U.S. did not use volley sights on the 1917 or stock disks. The British, when refurbing these for use in WWII for the Home Guard (look up a series called Dad's Army on youtube which features these), did something called the Weedon repairs which removed the stock disk and replaced the hole with a plug, removed any volley sights and I believe ground the volley sight plate, and marked the stock with a star to indicate repairs had been done. This is different than the asterisk mark on the receiver and bolt mentioned below which was done in WWI due to changes in the model.
There are some very rare original prototype P-13's out there which were made in England prior to WWI and were originally chambered in a hot 7mm round--the .276 Enfield. Not a specialist on those but I believe the P-13's were made at RSAF Enfield for trials--they will not have American mfg. markings and are very rare--only a handful are still known to be in existence, even fewer in their original chambering.
Then WWI intervened and Great Britain found itself desperately short on rifles due to heavy losses. To that end, the British contracted with Remington and Winchester (the Eddystone plant was a separate subsidiary of Remington at a new plant in PA which was a former Baldwin Locomotive factory). The Remington P-14's were made at Ilion, NY, and Winchester made theirs at New Haven, CT.
The early production of P14's had a flat faced barrel like the Mauser it was derived from and slightly shorter bolt projections for the extractor, and locking lugs. However, most of these were changed to a later std. that are marked with an asterisk on both the bolt and receiver which the barrel has a cut in the flat face for an extractor and the bolt projections were made slightly longer for the extractor lug and the other locking lug. A no asterisk bolt is required if you have an asterisk barrel. If you have an asterisk on the bolt and receiver, and the barrel has not been changed, then all is well. Otherwise a flat faced barrel has to be inlet so that the later asterisk model bolt will lock.
The markings on the receiver will be different as well--the Brits stamped their rifles everywhere with inspection stamps and there will be no ordnance bomb on the receiver. The magazines are different too and due to parts incompatibility at the time, a particular P14 magazine made at one plant might require fitting for another. Remington P14's will have RE in a circle, Winchesters have different markings but will include a W somewhere, and Eddystone will receivers will be marked ERA. 1917 rifles will have different markings, obviously.
Rimlock when firing from the magazine can be an issue if you do not follow proper loading techniques for rimmed cartridges. Feeding of the P14 is generally inferior to the 1917 because the P series was originally designed for a rimless Mauser type cartridge mentioned above. WWI was not the time to switch cartridges so the Brits soldiered on with the .303 British. In the P14, it is like a pussycat if the rifle is in full military trim with not much recoil and considerable accuracy.
People can rechamber the rifle and Century sold a .300 Win Mag conversion for awhile which works better in the P14 than the 1917 due to differences in the receiver and bolt facing (1917 bolt facing is designed for the .30-06 while the P14 bolt is designed for a rimmed cartridge) and thus allows a bigger case head than does the 1917 without work. The 1917 rifle has the U.S. coned shaped breech which makes these barrels more difficult to rechamber so a common rechamber was the .308 Norma Magnum which only requires a reamer. At this point, rechambering the rifle for sporting cartridges is probably a losing proposition in money, use, and time. The Canadians did something like the .308 Norma with their .303 Epps which is an improved .303 cartridge that upgrades ballistics to about a .308 equivalent. Epps himself only recommended doing this in the P14 but not the No. 1, Mk 3. I also think there are some other wildcats of the .303 that often use the P14 as a base due to the receiver's strength.
A lot of parts will interchange between the P14 and 1917 Rifle but the bolt and firing pin, barrel, ejector spring, ejector, magazine shell, spring, and follower, stock, and the odd stuff the Brits used like volley sights and stock disks are distinct. The rear sights are also different as they are calibrated for their particular issued ammo--however, they look similar and sometimes people have substituted the wrong rear sight.
Offhand, things like triggers, safeties, bolt parts other than the firing pin, springs other than the ejector, barrel bands, front sight bases and sights, etc. (probably forgetting some as this is by memory) interchange theoretically but often variations due to changes over time in production in a particular plant or between makers might require fitting for any particular part to a particular rifle.
Safety concerns
Last but not least. If the rifle is marked EY, it was determined by armorers to only be used in an emergency for a variety of factors. If it was marked DP, it is a drill rifle and many of these were dewatted by drilling a hole through the chamber of the barrel and through the handguards and stock. Some unscrupulous sellers have sometimes covered up the holes with handguards to get a higher price--check before you shoot it. It is also possible that bubba did some welding or some other unsafe practice to "fix" the hole in the chamber.
Too much to go into on firing DP rifles with live ammo or using a DP receiver so my advice is to seek out a gunsmith if your rifle is so marked. I would not fire an EY rifle nor use the receiver for building a sporter. An enterprising researcher has uncovered some pretty serious defects discovered post war regarding Eddystone receivers that at first glance seem worse than the low numbered receiver problems of early Springfields. We do not have similar access to British archives to determine if the problems in heat treatment of receivers was not present in the Eddystone P14's so if you do have an Eddystone-ERA make, have it checked by a gunsmith before firing.
