Sibling transitions are between screens that share a parent (album - photos, profile - sections, a task flow - tasks).
- Siblings: same or are logically related to each other.
- Siblings always move together. e.g. the example below: top navigation (parent) - content below (siblings)

Sibling Transitions

"At the top level of an app, destinations are often grouped into major tasks (and the tasks may not relate to one another)." Therefore don't use slide in/out for these screens since they may mislead users to think that they are hierarchical instead use fade-through.


Top-level Transitions

"Peer transitions occur between screens at the same level of hierarchy." Two kinds of peer transition are sibling transitions and top-level transitions.

University of Michigan - Ann Arbor

"Navigational transitions occur when users move between screens, such as from a home screen to a detail screen."

They help users understand the hierarchy and relation to the surfaces on the interface. 

-  Navigation and motion
-  Hierarchy

Navigation Transitions

Material Design Documentation

Hierarchical transitions are used to demonstrate that the user is moving up or down a level in the application. This can also demonstrate a parent-child relationship between surfaces. Parent surfaces have a higher level of hierarchy. 

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Related

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