Site engineers have similar jobs to construction (site) managers on a construction project. They manage parts of a construction project (also known as packages), providing technical advice, supervising staff on site and ensuring that their packages are completed on time and within budget.
The main difference between site managers and site engineers is that site engineers tend to have a more specific, technical knowledge and expertise. Site engineers typically come from a civil, structural, building services, architectural background and manage packages related to those areas.