Assign Separate Standard Action Overrides for Different Experiences

The action override screen for standard actions, like New, View, and Edit, has gotten a makeover. Now you can easily assign different overrides for Salesforce Classic, Lightning Experience, and mobile. For example, for the same standard action, you can set a Visualforce page override in Salesforce Classic, a Lightning page override in Lightning Experience, and a Lightning component override in mobile. This change applies to Lightning Experience, Salesforce Classic, and all versions of the Salesforce app.
Available in: Group, Professional, Enterprise, Performance, Unlimited, Contact Manager, and Developer Editions

Action overrides across environments

When setting up a Lightning Experience override with a Lightning page, only record pages assigned as the org default are supported.