The Titan Xp solution is intended for gaming as well as demanding appliactions such as Maya and Premier Pro, while the Quadro eGPU mainly focuses on engineering-grade applications and certifications.
https://www.notebookcheck.net/Nvidia-is-bringing-Titan-Xp-and-Quadro-external-GPU-solutuins-to-notebook-creative-professionals.239788.0.html