Esperanto and Novial are two different constructed international auxiliary languages. Their main difference is that while Esperanto is a schematic language, with an unvarying grammar, Novial is a naturalistic language, whose grammar and vocabulary varies to try to retain a "natural" sound. Demographically, Esperanto has thousands of times more speakers than Novial.

Both Esperanto and Novial are written using versions of the Latin alphabet. The Esperanto alphabet has 28 letters: 22 without diacritics and 6 with diacritics unique to Esperanto: ĉ, ĝ, ĥ, ĵ, ŝ and ŭ. Novial uses the standard 26 letters of the Latin alphabet with no diacritics.

In Esperanto one letter corresponds to one phoneme and one phoneme to one letter: there are no digraphs. Novial has 3 digraphs: ch, sh and qu; c and q are unique to these digraphs (except in foreign proper nouns) and permit no ambiguity; when s and h are separate phonemes this is indicated by separating with a hyphen: s-h. Novial permits some 2-vowel combinations to be pronounced either as 2 separate vowels or as diphthongs; for example, au, eu and oi may be pronounced as a + w, e + w and o + y, respectively, and ie, io and ia as y + e, y + o and y + a, respectively.

In handwriting neither Esperanto nor Novial presents any problem. However, the diacritics of Esperanto require special methods for typing and printing. The original method was a set of digraphs now known as the "h-system", but with the rise of computer word processing a so-called "x-system" has become equally popular. These systems are described in the article Esperanto orthography. However, with the advent of Unicode, the need for such work-arounds has lessened.

The personal pronouns of Esperanto all end in i and some may be difficult to distinguish in a noisy environment (especially mi and ni). The personal pronouns of Novial use various vowels making them more distinct, although some differ only in the initial consonant (e.g. nus, vus and lus). A later form of nus – nos, more distinct from vus – has sometimes been used. Novial does not distinguish familiar and polite forms of “you” (e.g. French tu and vous). Novial's inventor argued that such a distinction has no place in a language intended solely for international use. The distinction is available in Esperanto ^{[citation needed]} but is little used in practice.

² tiu, "that person", is usually used in this circumstance, because many people find it unnatural to use "it" referring to humans.
Apart from Ĝiism and Giism, Hiism and Riism as proposed reforms replace "Fundamento"-pronouns (ri instead of "li, ŝi, ĝi"; or "li" as utrum and hi instead of Fundamento "li"). Other proposals are variations of those four.

³iŝi, iĝi and by extension iri are proposed neologisms

The Novial system displays a systematic correspondence between singular and corresponding plural forms (i.e. vu, vus; lo, los; la, las; lu, lus; le, les). Strictly speaking "we" is not the plural of "I", because "many I’s" is nonsensical. Jespersen suggested that nu, the singular of nus, could be used as a "royal we". The optional marking of sex in Novial, especially in the third person plural, permits greater flexibility than in Esperanto, at least in this case. Exactly the same system is applied to other pronouns and to nouns with natural sex differences.