我猜你是从项目管理角度来问的。我的理解是这样的：
项目经理负责单一项目。项目集经理负责为带来的附加效果而统一管理的一组项目，这些项目由不同的项目经理负责，他们向项目集经理报告项目绩效以及可能影响其他项目的变更。
高级项目管理师和项目经理证有何区别
高级项目管理师是劳动保障部颁发的管理类职业资格证，没有行业限制，并
且全国通用，项目经理一般是指一个职位。建设部有“项目经理”的认证，是针
对建设工程方面项目经理的，项目经理现已被建造师锁取代.
项目经理 高级项目管理师 高级项目管理师考试 高级项目管理师用处 项
目管理师有用吗 高级项目管理师论文 高级项目管理师报名条件
单 位：中国建筑设计研究院人才培训中心
招生办：姜老师
What is the difference between a project manager and a project management professional?
A project manager is responsible for leading a specific project from start to finish, ensuring that it is completed on time, within budget, and meets the project goals and objectives. They are responsible for managing the project team, communicating with stakeholders, and making decisions that impact the project's success.
A project management professional, on the other hand, is someone who has obtained a certification in project management, such as the Project Management Professional (PMP) certification. They have demonstrated a certain level of knowledge and expertise in project management principles, tools, and techniques. They may work as project managers, but they can also work in other roles within project management, such as project coordinators, project analysts, or project consultants.
