Although the concept of a boundary type is fairly unambiguous (wall, stagnation inlet, etc.), models need additional information to deal with the type. Conditions provide this information. For example, with a boundary of type wall, the conditions will specify whether this is to be a no-slip wall, a slip wall or a moving wall. The conditions will also tell us whether we want to apply a specified temperature (Dirichlet) thermal boundary condition or a specified heat flux (Neumann) thermal boundary condition.
The types and conditions inform models how to deal with a boundary (or region or interface) but they do not specify actual numerical input. These numbers are provided by values.