If you can name the case, the explanations are probably in the decision.
If you can't name the case, understand that there are many decisions by the Ninth Circuit that involve copyright infringement. Some of which even reversed the court's earlier decisions. Too many to make it worth taking the time to find one.
Therefore, I'll give you a simple example.
Plot - Earth is invaded by extraterrestrial beings bent on either destroying or enslaving humanity and taking over the Earth for any number of reasons. There are dozens, if not hundreds, of stories, novels, movies and TV shows with the same plot.
Sequence of Events - Arrival, attack, domination, destruction, resistance, victory over the aliens (or not). Handled differently in each.
Earth vs the Flying Saucers has the same plot as Independence Day and V but that's where the similarity ends.