Installation method - pip or installer?

[ehrlichja]

The AWS docs instruct to manually download and use an installer: https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/install-sam-cli.html
This AWS blog post instructs to use pip: https://aws.amazon.com/blogs/apn/using-gitlab-ci-cd-pipeline-to-deploy-aws-sam-applications/

Are they equally valid? Is one preferable for some reason?