A national emblem is an emblem or seal that is reserved for use by a nation state or multi-national state as a symbol of that nation.
Other national symbols, such as national birds, trees, flowers, etc., are listed at lists of national symbols.
The design of an emblem is different to that of a coat of arms which should follow the rules of heraldry and so contain a shield (escutcheon) in the center.
However, many unheraldic national emblems are colloquially called national coats of arms anyway, because they are used for the same purposes as national coats of arms.
[3] The same for some national coats of arms like the Great Seal of the United States which is actually a coat of arms (achievement) on a seal.