Hi, here is the history of changes on the Well Architected Framework : https://docs.aws.amazon.com/wellarchitected/latest/framework/document-revisions.html
To point out specifically,
The below definition of level of efforts is added and also called out in each of the steps " The level of effort is categorizing the amount of time, effort, and complexity a task requires for implementation. Each organization needs to consider the size and expertise of the team and the complexity of the workload for additional context to properly categorize the level of effort for the organization. • High: The work might take multiple weeks or multiple months. This could be broken out into multiple stories, releases, and tasks. • Medium: The work might take multiple days or multiple weeks. This could be broken out into multiple releases and tasks. • Low: The work might take multiple hours or multiple days. This could be broken out into multiple tasks. "
The recommendations and best practices have been updated inline with a risk rating. These are on appendix.
There are no major changes on this version, but we recommend picking up the latest version and also use the Well Architected tool for reviewing the architecture - https://docs.aws.amazon.com/wellarchitected/latest/userguide/intro.html
If you know the previous version number, you can use the CLI See https://awscli.amazonaws.com/v2/documentation/api/latest/reference/wellarchitected/get-lens-version-difference.html
aws wellarchitected get-lens-version-difference --lens-alias arn:aws:wellarchitected::aws:lens/wellarchitected --base-lens-version <version>