Site Architect
A site is the central point where all of the Business Intelligence comes together. The SharePoint site is the location that unifies the collaboration, the teams, the documents, and the entire project. The site architect is the person responsible for creating and maintaining the SharePoint operations.

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Site Administrator
A site has to be managed after it has been designed. The role of the site administrator is to bring the different users together, organize the project, create the rules of collaboration, bring uniformity to the system, and engage in the Business Intelligence practices for the business group. Additionally, server farms can be created that will unify multiple SharePoint servers across different and multiple projects.

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Site Developer
The developer is the front end of the system unit. They bring together the documents, the users, make the collaboration possible, and put it all in the software. The developer takes the rules, notions, and processes and makes a website with the information that will be the central share point of the activity.
Images Credit: Microsoft