Due to the fact that this is a remake, numerous changes have been made to the story for improvement. Here I will detail the changes to perk everyone's interest (may be some spoilers):
-Names of protagonist and antagonist have been changed. Their personalities and character have been altered. Caleb is replaced with Logan and Tchernobody is replaced with Garibaldi. Character development of all characters is improved.
-Time of story is changed to 1918 instead of 1872.
-Antagonist isn't plotting to curse Earth, but seeks to exterminate mankind.
-There is no festival being held in the protagonist's home city that is postponed due to the invasion.
-The characters of Cecil (though he is still mentioned), Penelope, Erdrick, Eliza, Iconoclast I and VIII have been removed.
-The flashback scenes involving Cecil and Iconoclast IX have been removed.
-The protagonist is not captured aboard the ship.
-Edward plays a lute, not a harp.
-Iconoclast IX's wife did not die. The couple did have a child who unfortunately died.
-The swords of Ice and Storms have been renamed Water and Sky.
-Edward wielded the sword of Earth instead of the sword of Fire. The Iconoclast royal family was never in possession of one of the swords.
-The sword of Water was in possession of Cecil.
-The sword of Fire was owned by Garibaldi's father, an archmage.
-Murlock isn't aware of protagonist when he first enters the realm.
-The protagonist meets the spirit of king Iconoclast IX (and the queen) at the Iconoclast castle.
-The Cabal are replaced with the Scourge.
-The protagonist becomes involved in the flashback scene involving the antagonist's curse and the events leading up to it.
-Lazarus is no longer a soothsayer, but now a powerful wizard. The castle where a large portion of the game is set is no longer a memorial to him, but his home. He was the creator of the elemental swords (except the Sword of Darkness). The castle is not destroyed at the end. The protagonist never meets Lazarus.
-Protagonist is to be executed instead of being imprisoned in the dungeon.
-Edward and Minerva are cursed by the swords of Earth and Water and later freed by their power.
-Edward, Murlock, and Minerva are never aware of the protagonist's former ties to the antagonist.
-Edward and the protagonist free Minerva before the protagonist's battle with the antagonist.
-Antagonist is mortally wounded not by the protagonist but by his unseen master.
-The sword of Iconoclast, not Edward's harp is what undoes Garibaldi's curse over the land.
-Leoric (first introduced in part 2) is captain of the guard.
-Agnes is not a newborn baby, but instead is already a young woman when the protagonist meets her.
-The medallion is given to the protagonist by Murlock.