The term asset describes the resources or elements of an advertising campaign that are used to deliver the message. These can be images, videos, audio files, text, logos, graphics or other creative content used to present the product or service. 

An asset is typically created in advance and then used in various promotional materials.

Ads, derived from "advertisement", means the actual advertising material that is delivered to an audience, e.g. by an ad server. This can take the form of an ad banner (display), videos, audio spots or other advertising formats.

The ad is the end product that contains the message of the campaign, is enriched in the context of the AdSchedule with further content, such as the target URL, and is seen or heard by the target group.