Characteristics
Besides their fairly consistent ergative alignment and their generally agglutinative morphology (despite a number of not entirely predictable morpheme mergers), Hurrian and Urartian are also both characterized by the use of suffixes in their derivational and inflectional morphology (including ten to fifteen grammatical cases) and postpositions in syntax; both are considered to have the default order subject–object–verb, although there is significant variation, especially in Urartian. In both languages, nouns can receive a peculiar "anaphoric suffix" comparable (albeit apparently not identical) to a definite article, and nominal modifiers are marked by Suffixaufnahme (i.e. they receive a "copy" of the case suffixes of the head); in verbs, the type of valency (intransitive vs transitive) is signalled by a special suffix, the so-called "class marker". The complex morpheme "chains" of nouns and verbs follow roughly the same morpheme sequences in both languages. In nouns, the sequence in both languages is stem – article – possessive suffix – plural suffix – case suffix – agreement (Suffixaufnahme) suffix. In verbs, the portion of the structure shared by both languages is stem – valency marker – person suffixes. Most morphemes have fairly similar phonological forms in the two languages.
Despite this structural similarity, there are also significant differences. In the phonology, written Hurrian only seems to distinguish a single series of phonemic obstruents without any contrastive phonation distinctions (the variation in voicing, though visible in the script, was allophonic); in contrast, written Urartian distinguishes as many as three series: voiced, voiceless and "emphatic" (perhaps glottalized). Urartian is also characterized by the apparent reduction of some word-final vowels to schwa (e.g. Urartian ulə vs Hurrian oli "another", Urartian eurišə vs Hurrian evrišše "lordship", Hurrian 3rd person plural enclitic pronoun -lla vs Urartian -lə). As the last two examples shows, the Hurrian geminates are also absent in Urartian.
In the morphology, there are differences as well. Hurrian indicates the plural of nouns through a special suffix -až-, which only survives in fossilized form merged into some case endings in Urartian. Hurrian clearly marks tense or aspect through special suffixes (the unmarked form is the present tense) whereas Urartian has not been shown to do so in the attested texts (the unmarked form functions as a past tense). Hurrian has special negative verbal suffixes that negate a verb and are placed before the ergative person agreement suffixes; Urartian has no such thing and instead uses negative particles that are placed before the verb. In Hurrian, only the person of the ergative subject is marked obligatorily through a suffix in a verb form, whereas the absolutive subject or object is optionally marked with a pronominal enclitic that need not be attached to the verb and can also be attached to any other word in the clause. In Urartian, the ergative suffixes and the absolutive clitics have merged into a single set of obligatory suffixes that express the person of both the ergative and the absolutive participant and are an integral part of the verb. In general, the profusion of freely moving pronominal and conjunctional clitics that characterize Hurrian, especially that of the Mitanni letter, has few parallels in Urartian.
Urartian is closer to the so-called Old Hurrian variety (mostly attested in Hittite documents) than to the Hurrian of the Mitanni letter. For example, both use -o-/-u- (rather than -i-) as the marker of transitive valency and both display the plural suffix -it-, expressing the number of the ergative subject and occupying a position before the valency marker.
Read more about this topic: Hurro-Urartian Languages