Aldehyde and Formaldehyde

Aldehyde noun - Any of a class of highly reactive chemical compounds; used in making resins and dyes and organic acids.

Formaldehyde and aldehyde are semantically related. In some cases you can replace term "Formaldehyde" with "Aldehyde", this nouns are similar.

Formaldehyde noun - A colorless poisonous gas; made by the oxidation of methanol.

Aldehyde and formaldehyde are semantically related. Sometimes you can use "Aldehyde" instead a noun "Formaldehyde".