These are all words for something that you say or write, especially something that gives information or an opinion.
statement something that you say or write that gives information or an opinion, often in a formal way: A government spokesperson made a statement to the press. comment something that you say or write that gives an opinion on something or is a response to a question about a particular situation: She made helpful comments on my work. announcement a spoken or written statement that informs people about something: the announcement of a peace agreement remark something that you say or write that gives an opinion or thought about somebody/something: He made a number of rude remarks about the food. declaration (rather formal) an official or formal statement, especially one that states an intention, belief or feeling, or that gives information: the declaration of war observation (rather formal) a comment, especially one based on something you have seen, heard or read: He began by making a few general observations about the report.
COMMENT, REMARK OR OBSERVATION? A comment can be official or private. A remark can be made in public or private but is always unofficial and the speaker may not have considered it carefully. An observation is unofficial but is usually more considered than a remark.
PATTERNS AND COLLOCATIONS • to make a(n) statement/comment/announcement/ remark/declaration/observation • to issue a(n) statement/comment/announcement/ declaration • a(n) statement/comment/announcement/remark/ declaration/observation about/on something • an official statement/comment/announcement/ declaration • a public statement/comment/announcement/remark/ declaration • a private statement/comment/remark/observation