Differences between the old and the new orthography

1. Change in front of letters of assimilative softness: песня, свет, instead of песьня, сьвет.
2. Soft sign
   Soft sign
   The soft sign , also known as yer, is a letter of the Cyrillic script. In Old Church Slavonic, it represented a short front vowel. As with its companion, the back yer, the vowel phoneme it designated was later partly dropped and partly merged with other vowels...
   
    is no longer written between double consonant
   Consonant
   In articulatory phonetics, a consonant is a speech sound that is articulated with complete or partial closure of the vocal tract. Examples are , pronounced with the lips; , pronounced with the front of the tongue; , pronounced with the back of the tongue; , pronounced in the throat; and ,...
   
   s: каханне, instead of каханьне.
3. Particle
   Grammatical particle
   In grammar, a particle is a function word that does not belong to any of the inflected grammatical word classes . It is a catch-all term for a heterogeneous set of words and terms that lack a precise lexical definition...
   
    не and preposition без are written unchanged, independently of pronunciation
   Pronunciation
   Pronunciation refers to the way a word or a language is spoken, or the manner in which someone utters a word. If one is said to have "correct pronunciation", then it refers to both within a particular dialect....
   
   : не быў, instead of ня быў; без мамы, instead of бяз мамы (compare with English
   English language
   English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...
   
    definitive article "the"
   THE
   THE is a three-letter acronym that may refer to:*Technische Hogeschool Eindhoven , a Dutch university of technology...
   
   ).
4. Loanword
   Loanword
   A loanword is a word borrowed from a donor language and incorporated into a recipient language. By contrast, a calque or loan translation is a related concept where the meaning or idiom is borrowed rather than the lexical item itself. The word loanword is itself a calque of the German Lehnwort,...
   
    orthography is regulated: akanye
   Akanye
   Akanye or akanje is a phonological phenomenon in Slavic languages in which speakers pronounce the sound a instead of o. The most familiar example is probably Russian akanye...
   
    is preserved in all cases except of ten words, such as рэволюцыя, совет etc.; central-European l is transmitted as hard and not soft, as in Russian language; variants of writing the sound ф with letters п, хв, х, т are removed; -тар, -дар at words' ends are replaced with –тр, -др, for example: літр, instead of літар; words' ends -ый, -iй are used where appropriate, for example: алюміній instead of алюміні.
5. Orthography of personal name
   Personal name
   A personal name is the proper name identifying an individual person, and today usually comprises a given name bestowed at birth or at a young age plus a surname. It is nearly universal for a human to have a name; except in rare cases, for example feral children growing up in isolation, or infants...
   
   s is regulated so that vernacular
   Vernacular
   A vernacular is the native language or native dialect of a specific population, as opposed to a language of wider communication that is not native to the population, such as a national language or lingua franca.- Etymology :The term is not a recent one...
   
    forms are replaced with canonical Orthodox
   Russian Orthodox Church
   The Russian Orthodox Church or, alternatively, the Moscow Patriarchate The ROC is often said to be the largest of the Eastern Orthodox churches in the world; including all the autocephalous churches under its umbrella, its adherents number over 150 million worldwide—about half of the 300 million...
   
    forms, for example: Юрый instead of Юрка, Юры, Юра or Юрась.
6. In morphology
   Morphology (linguistics)
   In linguistics, morphology is the identification, analysis and description, in a language, of the structure of morphemes and other linguistic units, such as words, affixes, parts of speech, intonation/stress, or implied context...
   
   , ending –а/-у in genitive case
   Genitive case
   In grammar, genitive is the grammatical case that marks a noun as modifying another noun...
   
    is regulated as –а, as in Russian language, and not as -у, as in certain dialects of the vernacular. Also unified is the spelling of names in dative
   Dative case
   The dative case is a grammatical case generally used to indicate the noun to whom something is given, as in "George gave Jamie a drink"....
   
    and prepositional case
   Prepositional case
   Prepositional case is a grammatical case that marks the object of a preposition. This term can be used in languages where nouns have a declensional form that appears exclusively in combination with certain prepositions...
   
   .