The FN FAL (Fusil Automatique Léger) was designed by Dieudonné Saive and Ernest Vervier from 1947 to 1951. It is also called the FN LAR (Light Automatic Rifle), the English translation of its Belgian French name. The fact that there are so many variants, made by different countries and different names for the same models, causes a lot of confusion regarding what particular FAL is in what movie. For the most part, only the major variants of the gun will have been seen in movies with wide distribution, (the original Belgian version, U.S. versions, the Israeli Versions and British/Commonwealth Version). The early FAL prototypes were chambered in intermediate cartridges like 7.92x33mm and .280 British, in an attempt to create an assault rifle along the lines of the Nazi German Sturmgewehr 44, but after 7.62x51mm NATO was adopted as the standard NATO rifle cartridge, the FAL design was altered to accommodate the more powerful round.
The L1A1, also commonly referred to as the SLR (Self Loading Rifle) is the British version of the FN FAL which also saw extensive service with other Commonwealth countries. They are commonly referred to as "inch pattern" rifles (as opposed to the FN FAL which is "metric pattern") due to the rifle being designed and tooled to imperial measurements, but they also feature a number of design changes and improvements (it is these changes in the pattern which make inch and metric parts generally non interchangeable, rather than the minuscule differences in the measurements). These differences include a larger magazine release, a different selector switch, relocated take-down lever, a folding charging handle, "sand cuts" on the bolt, skeletonized front sight wings and a larger flash hider, along with different furniture depending on the time period and country.
The Ishapore 1A1 SLR is the domestically produced Indian variant of the FAL rifle. It is not however a licensed copy, but is instead reverse engineered from the commonwealth inch pattern rifles. However, the Indian designers of the weapon made alterations to the design resulting in a mix between a metric and inch pattern rifle without the parts compatibility of other FAL variants and copies.
The IMBEL M964 A1 ParaFAL is a updated version of the Imbel M964 (a copy of the FN FAL 50.00) featuring a shorter barrel and light-weight polymer parts instead of the traditional aluminum. Available as either a parts kit or as a completely new weapon, the ParaFAL is currently used by many Brazilian police and military units.