Dimensions: A Dimension is a natural existence that has an immeasurable property of space, in itself it is not technically physically. However, it can contain all forms of matter, energy, and properties that it takes to build a universe. A dimension can exist without a universe in it, which is usually presented as a white void. Inside, a universe can be created; And multiple universes can exist in the same dimension. They are disconnected from the Omniverse as well, they are also unaffected by multiverse occurrences.
Timelines: a timeline is the natural progression of a universe from start to finish. Every universe begins with one timeline, while universes function independently from one another; an alternative timeline cannot exist unless it is created by changing previously established events. Creating a new outcome, remarkably through time travel. An alternative timeline usually rewrites the original, changing how the universe continues to unfold; but previous timelines can be revisited through extra-dimensional means. These timelines all inevitably trace back to the same universe. One universes timeline cannot affect another through typical time travel means, meaning if something where to change in “Universe A”; “Universe B” will remain the same.
Universes: when multiple universes exist in the same dimension they become a multiverse. Usually due to their proximity, natural events of the universes play out very similarly; with minor differences between each other. These universe become parallel universes to each other. Even though they share some common denominators, these universes exist completely independently from each other; and their own events are isolated and do not affect one another.