Communication vs. Communications

差一个“s”，含义差许多。

https://www.csusm.edu/communication/major_differences.html

Communication: 

• “How messages are received and interpreted… Communication is about forming relationships with others. A human element.  Communication is something that we do on a daily basis.”   Dr. Wagner, Xavier University[2]

• “The communicating of information.  The exchange of information between individual, for example, by means of speaking, writing, or using a common system of signs of behavior.” Dr. Larson, University of Utah[3]

• “Communication is a systemic process in which individuals interact with and through symbols to create and interpret messages” Dr. Julia Wood, University of North Carolina at Chapel Hill[4]

Communications:

• “The distribution of messages… Communications is a technical term that defines the act of mass communications.  It is things such as radio transmissions and technology.”  Dr. Wagner, Xavier University[5]

• “The technology and systems used for sending and receiving messages, for example, postal, telephone, radio, TV and the Internet.  The tactics used to execute a marketing strategy, for example, advertising, PR, Sales promotion, events…” Dr. Larson, University of Utah[6]

“…Communication is the strategy and creativity.  It is the planning and managing that takes place first, and then communications are employed (through various media, whether the medium is print or Web or whatever) to get those formulated messages across.”  Joshua De Lung, Executive Editor, Relatively Journalizing[7]

简单地说，你和我在微信上聊天，是communication。我们这种聊天需要一个“媒介”，比方说微信。微信是一种communications方式。

你也可以查一下 sale vs sales. Sales promotion 不是sale promotion。