LUNEX5 is a new Free Electron Laser (FEL) source project aimed at delivering short and coherent X-ray pulses to probe ultrafast phenomena at the femto-second scale, to investigate extremely low density samples as well as to image individual nm scale objects. The proposed machine layout is based on a 400 MeV superconducting Conventional Linear Accelerator (CLA) mainly composed of 2 XFEL type cryomodules together with a normal- conducting high brightness photo RF gun. Such a mature and reliable technology is able to deliver high quality electron bunches up to few kHz suitable for user experiments. Furthermore, the last decade improvements in synchronization and stability offer a fertile land to explore the different and innovative seeded FEL operations aiming at producing higher coherence and energetic X-rays for the pilot user benefits. In parallel of the CLA branch, the very promising and highly innovative Laser Wake-Field Accelerator (LWFA) enables to produce very short electron bunches in the range of the femto- second and high peak current up to few GeV, as a FEL bench test using the same undulator lines.