What are the two project layouts offered by Rancher on installation?
Project is a Rancher specific concept. A Project can have multiple Kubernetes namespaces.

The System Project has all the Kubernetes system components like kube-dns, ingress etc. Think of it like System Services running on a machine/laptop.

Default project is where you can launch your workloads to start with. Similar to a scratchpad.

You can create new projects too. For example, Web App, Database, etc. Or it could be based on different users using the cluster. Project-For-Bob, Project-For-John.