A litany is a ceremonial form of prayer. It consists of a series of invocations (calls) or petitions followed by responses: "The language of the litany in the Book of Common Prayer is considered beautiful." Litany may also refer to any recitation or recital of lines and to a prolonged or monotonous account: "His recital of mishaps was a litany of bad luck." Liturgy refers to a form of public worship, to a ritual of services. It is applied especially to what is known as the Eucharist in the Eastern Church and as the Mass in the Western Church."At the seminary, he studied liturgies, the art and science of conducting public worship that is known as liturgy."
Dictionary of problem words and expressions. Harry Shaw. 1975.