Comparison between Interlingue and Interlingua
Interlingue and Interlingua are constructed international auxiliary languages. Nomenclature. Interlingu- applies to three international auxiliary languages: To avoid confusion, this article refers to Interlingue as Occidental until the name change in 1949 and Occidental-Interlingue afterwards, Interlingua de IALA as Interlingua, and any references to Interlingua de Peano as Latino sine flexione. History. Approximately 30 years older than Interlingua, the beginnings of Occidental-Interlingue reach back to 1894 when its founder Edgar de Wahl, until then an active Esperantist and one of its pioneers, chose to leave the language and begin creating his own after  the vote in 1894 to reform the language failed. De Wahl spent the years in between collaborating with other auxiliary language creators and working on his own language, which appeared for the first time in the book "Transcendental Algebra" by Estonian linguist Jakob Linzbach in 1921, followed by its announcement in the magazine Kosmoglott in February the following year. The beginnings of Interlingua reach back to 1924 and the foundation of the IALA by Alice Vanderbilt Morris and her husband Dave Hennen Morris. While the IALA originally did not intend to create its own language, it began showing an interest  in the possibility in the years after 1934 when it rejected the idea of a completely schematic auxiliary language, leaning towards a naturalistic language; at this time it began creating models for languages based on schematic languages like Ido and naturalistic languages like Occidental to aid it in deciding on which language model to adopt. Vocabulary and linguistic character. Both Occidental-Interlingue and Interlingua are naturalistic constructed languages based on common Western European vocabulary, and share approximately 90% the same vocabulary when orthographic differences and final vowels (filisofie vs. philosophia for example) are not taken into account. Despite this, prominent  supporters of both Occidental-Interlingue and Interlingua saw the similar vocabulary as superficial, and unrelated to the inherent character of their languages. Alexander Gode, one of the creators of Interlingua, believed that its grouping with Peano's Latino sine Flexione and Occidental-Interlingue as naturalistic planned languages was done "according to exclusively superficial and external similarities", and that it was the "idealism" of de Wahl that "prevented him from freeing himself from traditional Esperantism", an idealism that he defined as "subordinating the observed facts to the preconceived idea and ideal of what an auxiliary language should be." Derivation from verbs  in Occidental-Interlingue is regularized as much as possible using De Wahl's rule, while in Interlingua such a rule does not exist and so-called Latin double stem verbs (e.g. scriber to script-) are brought in without changes. Orthography. Interlingua uses traditional greco-roman orthography with digraphs such as ph and th, the vocalic y and doubled consonants (e.g. tyranno, emphatic and Christo instead of tirano, emfatic and Cristo). A so-called collateral orthography exists for those who prefer a simplified spelling. Grammar. Both Occidental-Interlingue and Interlingua are promoted as languages with an international vocabulary and minimal grammar , and a form of "modern Latin". A comparison of the basic grammar between the two languages (cited from the Grammatica de Interlingue in Interlingue by Dr. F. Haas and A Grammar of Interlingua by Alexander Gode and Hugh Blair) is as follows: Correlatives. The correlatives for both languages tend to follow a q-, t-, and al- distinction in which Occidental-Interlingue "tries to retain regularity as well", while in some parts Interlingua is more regular than Occidental (the universal series with "omne"), while in others not (e.g., the temporal series). Correlatives considered regular by Federico Gobbo in the source are  indicated in bold. Mutual influence. A certain amount of influence has taken place between the two languages. Influence of Interlingua on Occidental-Interlingue. After the standardization of Occidental in 1947 and the renaming to Interlingue there was a push towards more naturalistic forms, particularly by Ric Berger, who advocated replacing the optional -i adjectival ending with -e. After advocating for the change in April 1949 he began implementing it the following month in his own writing and most of the content in "Cosmoglotta", in addition to other changes such as "nostre" (our) and "vostre" (your) instead of "nor" and "vor ." The following April he defended the changes, denying that they were a "concession to the IALA" but instead a simple "concession to the general tendency towards greater naturalism found today in the interlinguistic movement", calling critics of the changes victims of "long-lasting habits" and an "optical illusion". Berger left his position as editor of "Cosmoglotta" soon after and eventually joined Interlingua in 1956.