Both of these tools are for GitHub and Cache (not Git and Cache, but with easy customization required to support some other Git server API over HTTP).
Cache Updater is a simple Cache task. You specify GitHub information (repository and user/pass if it's a private repo) and namespace. Then you set a schedule and that's it. Every time the tasks runs it downloads (and compiles) code from GitHub and into Cache Namespace.
CacheGitHubCI is a full fledged CI system. You may specify pre and post compile actions, unit tests, etc. The results and timings of each build and action are saved and there are DeepSee dashboards available. GitHub webhooks are supported, which allows running builds immediately after there is a new commit in a repository.
Which one you choose depends on your requirements. Cache Updater is very easy to set up, CacheGitHubCI offers more features.
Both of them are built atop GitHub COS API, which provides COS wrappers for GitHub API.