Both are fantasy and have the same fictional creatures
Prince Caspian is portrayed as a brave and honorable character in C.S. Lewis's "Chronicles of Narnia" series. He is depicted as a natural leader who is determined to reclaim the throne of Narnia from his evil uncle, King Miraz, and restore peace to the land. Caspian is also compassionate, kind-hearted, and willing to listen to the advice of others.
"Eragon" is told in third person limited, primarily following the perspective of the main character, Eragon. The narrative provides insight into Eragon's thoughts, feelings, and experiences, offering a more subjective view compared to third person omniscient.
Eragon
Ed Speleers played Eragon in the movie.
In Eragon the dragon is called Saphira and her rider is Eragon
Eragon does not have a religion.
Ed Speleers played the character of Eragon in the movie adaptation of the book "Eragon."
Characters: Eragon, Roran (Eragon's cousin), Arya (elf who got the egg to Eragon) Saphira (Eragon's dragon) Brom (storyteller/dragon rider/Eragon's dad), and galbatorix (main antagonist).
You may enjoy other fantasy series such as "The Inheritance Cycle" by Christopher Paolini, "The Lord of the Rings" by J.R.R. Tolkien, "The Chronicles of Narnia" by C.S. Lewis, or "The Wheel of Time" by Robert Jordan.
Eragon
Book one in the Inheritance Series is called Eragon. The only known riders in Eragon are Galbatorix and Eragon himself, though at the end of Brom's life Eragon learns that he too was once a rider.
The movie Eragon was filmed in Hungary.