Difference between Heir Presumptive and Eldest

HEIR PRESUMPTIVE vs ELDEST: NOUN

Someone who will inherit only if no better choice for an heir is born.
See heir apparent.
An heir who stands to inherit the estate, title, or office of an intestate ancestor, but whose claim can be defeated if a relative who is closer to the ancestor is born prior to the ancestor's death.
A person who expects to inherit but whose right can be defeated by the birth of a nearer relative

Superlative form of old: most old.; greatest in age or seniority.
The player on the dealer's left hand.
Born or living first, or before the others, as a son, daughter, brother, etc.; first in origin. See Elder.
Oldest; longest in duration.
Greatest in age or seniority.
First in order of birth

Oldest; most advanced in age; that was born first: as, the eldest son or daughter.

Succession, Peacock throne, Kingship, Dynastic, King, Prince consort, Princeling, Monarch, Figurehead, Prince regent, Coronation, Heir, Successor, Throne, Heir apparent

Paternal, First born, Largest, Most, Big, Tai, Wisest, Senior, Biggest, Greatest, Elderly, Oldest, Elder, First, Firstborn

Succession, Peacock throne, Kingship, Dynastic, King, Prince consort, Princeling, Monarch, Figurehead, Prince regent, Coronation, Heir, Successor, Throne, Heir apparent

Paternal, First born, Largest, Most, Big, Tai, Wisest, Senior, Biggest, Greatest, Elderly, Oldest, Elder, First, Firstborn

He is the son of Eliwood, the main character of Fire Emblem: The Blazing Blade, and heir presumptive of Pherae.
Frenchman, that he is not heir presumptive to another crown, and that he has previously taken the civic oath.
Prince Albert became King George VI and the young Princess Elizabeth became heir presumptive to the throne.
Known as "The Brat" in the Heraldic Circle, the Heir-presumptive lives up to her nickname.
Roger was made lieutenant of Ireland and was declared heir presumptive to the Crown.

Styx, who truly is eldest of them all.
Nissa, the Eldest Daughter of His Uncle Aurangzeb.
Agnello was succeeded by his eldest son Giustiniano.
In the doorway stands their eldest son Benjamin.
Our subject was the eldest; then came Prof.
She was the second eldest of twelve children.
The second eldest qualifying son would succeed if the eldest qualifying son say, had girls only.
Not listed above are Hugh Magnus, eldest son of Robert II, and Philip of France, eldest son of Louis VI.
Jesus to his eldest brother James, and after him for several generations to the eldest living representative of his family.
My youngest more than my eldest, eldest is just a bit pink but.