Difference between Chain and Redirect Action result types

Chain result type is used for Action Chaining which means that the source result invokes an entire other action, complete with it's own interceptor stack and result.
Redirect Action result type is used to redirect to another Action which means making your source Action, after it has successfully executed, result in a redirect.
As a rule, Action Chaining is not recommended. Redirect Result or the Redirect Action Result is preferred over Chain Result.