What's the difference between дочь and дочка? They seem synonymous, so how does one choose between one or the other?
Russian nouns have diminutive forms. In other words, we have the plain nouns - we'll call them "neutral", and then there are more "affectionate" forms of these same words. The word дочь daughter has two such forms: дóчка and дóченька. In terms of meaning, there's no difference between "дочь" and "дочка", however "доченька" expresses a certain love for this person.
Дочка is a diminutive form of the word дочь.
Diminutives, or words with diminutive suffixes, are markers of the speaker's linguistic consciousness. It should be noted that in the speech of women the number of diminutives prevails in comparison with the speech of men due to their emotionality. The term "diminutiveness" is traditionally defined as follows: "A generalized meaning of small volume, size, etc., usually accompanied by various emotional overtones - caressing (expressing caress/please), derogatory, etc.
The attitude of people to the use of diminutives is also ambiguous. Some "affectionate" forms cause rejection, bordering on aggression; forced not only to be indignant internally, but even to take certain actions, to fight back. Others have very strong feelings for such words and they add suffixes where necessary and not necessary. And there is no middle ground in this dispute: either love or hate.
Diminutive forms are primarily assigned to the family and household sphere of speech communication. For example, in speech, personal names in diminutive forms are used to express a benevolent, affectionate attitude of the participants in communication to each other.