Kinyarwanda and Kirundi are very similar in many aspects, but differ in several ways as well.
Tonal marking
Both languages are tonal languages. High and low tones (or H and L) are the essential tones and, having a phonemic distinction on vowel length, when a long vowel changes from a low tone to a high tone it is marked as a rising tone and when a long vowel changes from a high tone to a low tone, it is marked as a falling tone. This is often illustrated in Kirundi in Meeussen's rule. Propositions have also been made that tones can shift by a metrical or rhythmic structure.
1 These symbols are only used in transcription, for example in a dictionary, but in other forms of writing, plain vowels are used and letters are not doubled (unless if the word itself is spelt in that way).
There are many instances in which the two speech varieties of both languages have words that are slightly different. However, these differences do not continually recur. One has to memorize such differences as "-anga" in Kinyarwanda in contrast to "-anka" in Kirundi (meaning to dislike or hate), because the shift from "g" to "k" is extremely rare, with proof being words like "inka" (cow), "inkono" (pot) and many other words where "nk" is common in both dialects. Such minor variations involve different consonants, vowels or vowel lengths, tones or affixes.
^Rwanda and Rundi: Nationalencyklopedin "Världens 100 största språk 2007" The World's 100 Largest Languages in 2007; others: Lewis, M. Paul; Gary F. Simons; Charles D. Fennig, eds. (2015). Ethnologue: Languages of the World (18th ed.). Dallas, Texas: SIL International.
