How to identify what all changes we are migrating to our target instance

Summary:

We are doing our redwood development in our development instance for multiple modules.

After that, we will plan to migrate all changes in our UAT instance.

Question1- how we can identify/can we pull the list of changes which we done (related to each filed, business rules) before migrating it to the target instance?

Question2- how we can validate the changes in target instance (apart from manual validation) ?

Content (please ensure you mask any confidential information):

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):