An act of the executive branch

A decree is issued by the President of the Republic or the Prime Minister, according to their respective powers. It may specify how a law is to be implemented or address matters within the scope of regulatory authority.

A general rule or an individual decision

A decree may be regulatory, when it lays down general rules, or individual, when it concerns a particular situation. Naturalisation by decree illustrates this second category.

Note the distinction: a law is passed by Parliament; a decree is an act of the executive branch. Promulgating a law and signing a decree are therefore different procedures.