Symbol, emblem, attribute, type can all denote a perceptible thing that stands for or suggests something invisible or intangible.
Symbol and emblem are often used interchangeably but they can be so used as to convey clearly distinguishable notions.
Symbol is applicable to whatever serves as an outward sign of something spiritual or immaterial; thus, the cross is to Christians the symbol of salvation because of its connection with the Crucifixion; the circle, in medieval thought, was the symbol of eternity because it, like eternity, has neither beginning nor end.
This close and natural connection between the symbol and what it makes visible or partly intelligible is not always so strongly implied; it may be a traditional, conventional, or even an arbitrary association of one thing with another that is suggested.
Emblem , as distinguished from symbol , implies representation of an abstraction or use in representation; it is applicable chiefly to a pictorial device or a representation of an object or a combination of objects (as on a shield, a banner, or a flag) intended to serve as an arbitrary or chosen symbol of the character or history of one (as a family, a nation, a royal line, or an office) that has adopted it; thus, the spread eagle, the usual emblem of the United States, is found in its coat of arms and on some of its coins and postage stamps; the emblem of Turkey, a crescent and a star, appears on its flag.
Emblem is also applied to what is technically known in painting and sculpture as an attribute , some object that is conventionally associated with the representation either of a character (as a Greek divinity or a Christian saint) or of a personified abstraction, and is the means by which the character or abstraction is identified; thus, in fine art the balance is the emblem , or attribute , of Justice; the turning wheel, of Fortune; the club, of Hercules; and the spiked wheel, of St. Catherine of Alexandria.
Type , especially in theological use, is applied to a person or thing that prefigures or foreshadows someone or something to come and that stands therefore as his or its symbol until the reality appears. In theology, biblical interpretation, and religious poetry, it usually also implies a divine dispensation whereby the spiritual or immaterial reality is prefigured by a living person, event, experience, or the like; thus, in medieval religious poetry Jerusalem is the type of heaven (the heavenly Jerusalem); in allegorical interpretation of Scriptures, the paschal lamb is the type of Christ, the victim on the Cross.