A logo is a graphic mark, emblem, or symbol used to aid and promote public identification and recognition. It may be of an abstract or figurative design or to include the text of the name that it represents as in a wordmark.
A coin from early 6th century BC Lydia bearing the head of a roaring lion with sun rays
Red Cross and Red Crescent emblems
The Coca-Cola logo is identifiable in other writing-systems, here written in Cyrillic.
Nunc est bibendum (now is the time to drink), 1898 Michelin poster
An emblem is an abstract or representational pictorial image that represents a concept, like a moral truth, or an allegory, or a person, like a monarch or saint.
The Wilton Diptych (c. 1395–1399) features angels wearing White Hart (a deer), the personal emblem of King Richard II of England.
House of the Prince of Naples in Pompeii Triclinium Emblem on North Wall
"The big eat the small", a political emblem from an emblem book, 1617