"According to" and "in accordance with" are phrases used to indicate that something is based on or aligned with a particular source or set of rules, guidelines, or beliefs. However, there are slight differences in their usage and connotations. "According to" is used to attribute information, opinions, or statements to a specific source, such as a person, a book, a report, or a study. It implies that the information being presented is sourced from or derived from that particular authority. For example: "According to the weather forecast, it will rain tomorrow." "According to the article I read, the economy is improving." "In accordance with" is used to indicate compliance or conformity with a particular set of rules, guidelines, or principles. It suggests that the action or decision being taken is in alignment with the specified standards or requirements. For example: "In accordance with company policy, all employees must attend the safety training." "The project was completed in accordance with the agreed-upon specifications." Both phrases convey a similar meaning of being based on a source or adhering to certain principles, but "according to" focuses more on the source of the information, while "in accordance with" emphasizes compliance with established rules or guidelines.

They mean two different things. Use "according to" to say who said something or to cite a source. Use "in accordance with" to say someone is following a law or regulation or complying with an agreement. According to my neighbor, the house down the street has been sold. I always keep my lawn well-maintained in accordance with the neighborhood association's bylaws.