There are two main types of SCM software: 1) planning applications and 2) execution applications.
Planning applications use advanced algorithms to determine the best way to fill an order.
Execution applications track the physical status of goods, the management of materials, and financial information involving all parties.
Some SCM applications are based on open data models that support the sharing of data both inside and outside the enterprise (this is called the extended enterprise, and includes key suppliers, manufacturers, and end customers of a specific company). This shared data may reside in diverse database systems, or data warehouses, at several different sites and companies.
By sharing this data “upstream” (with a company’s suppliers) and “downstream” (with a company’s clients), SCM applications have the potential to improve the time-to-market of products, reduce costs, and allow all parties in the supply chain to better manage current resources and plan for future needs.
Increasing numbers of companies are turning to Web sites and Web-based applications as part of the SCM solution. A number of major Web sites offer e-procurement marketplaces where manufacturers can trade and even make auction bids with suppliers.
Source: http://searchcio.techtarget.com/sDefinition/0,,sid19_gci214546,00.html
that was indeed a very nice way of classifying SCM applications that makes it clear to even layman like us..thanks