What is the difference between fidic red book and silver book?

FIDIC Red Book for project design by the Employer and Silver Book for Design & Built by Contractor 

Red Book is for construction works where the design scope is the responsibility of the Employer.

unlike the silver book which is for turn key jobs where the works are to be designed by the Contractor.

In Red Book FIDIC Contracts, all the risks associated with design [variation in quantity, rates & any other additional requirements due to further change in tender design], except few, to be beared by the Employer. 

In Silver Book, all the risks associated with design to be beared by the Contractor.  

Different between the FIDIC Red and Silver books are; the Red book guidance for condition of contract for CONSTRUCTION for Building & Engineering works design by the employer and the Silver book guidance for the condition of contract for EPC/ TURNKEY PROJECT works.

Red book is for Employer designed project and silver book is used when there is EPC/Turnkey project.

The Construction Contract - Red Book, Conditions of Contract for Construction are recommended for building or engineering works designed by the Employer or by his representative, the Engineer.

The Plant Contract - Yellow Book, Conditions of Contract for Plant and Design-Build are recommended for the provision of electrical and/or mechanical plant, and for the design and execution of building or engineering works.

Red book (Construction Contract) is condition of contract for constraction and Silver book is conditions of contract for procurement and contruction.

The distinction is made in the scope of implied liabilities. In Silver Book contracts the Contractor bears full liability for achieving fitness for purpose. Red Book contracts retain such liabilities at the Employer.  

Red Book.......design is Employer's responsibility

Silver Book .....design is contractor's responsibility

Red Book contract :Project is designed by the employer

Silver Book Contract: Design Built by the contractor

Red book is  a Conditions of Contract for employer designed projects while the Silver book is for contractor designed EPC/Turnkey projects. The client bears the design related risks in Red book while the contractor bears design related risks of the Silver book.