In the Microsoft world, there are three classes of Architects; The Enterprise Architect, Solution Architect, and Infrastructure Architect.
Enterprise Architects have a broad view of the organisation and are akin to the city planners. They work with stakeholders, leadership teams and experts, to build a high level view of the organisations strategy and processes as it relates to information technology. Their objective is to ensure the business and IT are in alignment.
Solution Architects are responsible for transforming of the vision prescribed by the Enterprise Architect and designing its reality. They design the software solution which will solve the problems being discussed, and organise the development effort around it.
Infrastructure Architects take these requirements and design the environment required for the solution to success. Their focus is on the supporting infrastructure, the servers, hardware, networks, protocols, and also deal with issues such as storage, backup, and performance.