Undifferenced arms are coats of arms

Coat of arms

A coat of arms is a unique heraldic design on a shield or escutcheon or on a surcoat or tabard used to cover and protect armour and to identify the wearer. Thus the term is often stated as "coat-armour", because it was anciently displayed on the front of a coat of cloth...

 which have no marks distinguishing the bearer by birth order or family position. In the Scottish and English heraldic traditions, these plain coats of arms are legal property transmitted from father to eldest male heir, and are used only by one person at any given time. The other descendants of the original bearer could bear the ancestral arms only with some difference

Cadency

In heraldry, cadency is any systematic way of distinguishing similar coats of arms belonging to members of the same family. Cadency is necessary in heraldic systems in which a given design may be owned by only one person at once...

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