LambCI vs Test Kitchen: What are the differences?

Developers describe LambCI as "A continuous integration system built on AWS Lambda". LambCI is a package you can upload to AWS Lambda that gets triggered when you push new code or open pull requests on GitHub and runs your tests (in the Lambda environment itself) – in the same vein as Jenkins, Travis or CircleCI. On the other hand, Test Kitchen is detailed as "Integration tool for developing and testing infrastructure code and software on isolated target platforms". Test Kitchen has a static, declarative configuration in a .kitchen.yml file at the root of your project. It is designed to execute isolated code run in pristine environments ensuring that no prior state exists. A plugin architecture gives you the freedom to run your code on any cloud, virtualization, or bare metal resources and allows you to write acceptance criteria in whatever framework you desire.

LambCI and Test Kitchen belong to "Continuous Integration" category of the tech stack.

LambCI and Test Kitchen are both open source tools. It seems that LambCI with 3.6K GitHub stars and 210 forks on GitHub has more adoption than Test Kitchen with 1.62K GitHub stars and 543 GitHub forks.