• Substantive law defines rights, duties and offences — what the law is. Example: Muluki Civil Code 2074 (defines contract, ownership, marriage); Muluki Criminal Code 2074 (defines murder, theft and their punishments).
• Procedural law prescribes the method of enforcing those rights — how the law is applied. Example: Muluki Civil Procedure Code 2074, Muluki Criminal Procedure Code 2074, Evidence Act 2031, Court Management Act 2073.
Remember: procedural law is the machinery; substantive law is the product of the machine.