The key differences between CreateML and TuriCreate are:
CreateML only works on macOS 10.14+, where as TuriCreate is cross-platform and works on macOS 10.12+, Linux & Windows 10.
CreateML requires you to write Swift code in Playground, where as TuriCreate works using Python and can be written in any environment/IDE.
CreateML only allows you create custom models to solve a limited set of tasks (such as classification, text recognition and regression), where as TuriCreate allows you to create custom models to solve a variety of tasks not supported by CreateML, such as Style Transfer (similar to how Prisma works), Object Detection and Activity Recognition.
CreateML does not allow you to choose the model used for transfer learning (it uses VisionFeaturePrint_Screen), where as TuriCreate allows you to switch between multiple models (VisionFeaturePrint_Screen, Resnet-50 & MobileNet). Unfortunately, both frameworks do not allow you to choose your own model for transfer learning.
CreateML allows you to tune an extremely limited set of parameters for a particular ML task, where as TuriCreate gives you slightly more flexibility in terms of tuneable parameters.
Intro to Machine Learning on iOS with CreateML & TuriCreate — Part 2