Legacy services, such as existing mainframe or ERP systems, can expose services typically through proprietary interfaces such as LU6.2 ACCP, or SAP's BAPI. These services usually provide both behavior and information bound to that behavior. In other words, there is functionality and structure.
New services are those services created from the ground up as services. These services have behavior as well as information bound to the behavior, but are built from scratch as services, so there's not much further abstraction required (see next level up). They are typically Web Services but don't have to be as a rule.
Data services, as the name implies, are databases, data files, or other data stores that can produce and consume data. They support some behavior, but just enough to manage the data interaction services.
