What's the difference between workforce planning and succession planning?

In essence, workforce planning is concerned with the quantity and skills of the workforce 'as a whole' within a team/service/organisation, whereas succession planning is concerned with the requirements related to specific/critical posts. 

Workforce planning will often be driven by budgets, current and future customer/client demand, and overall recruitment.

There will be a focus on - 

• Trends, data, and demographics of users/stakeholders/employees
• Service plans
• Strategic and operational change management
• Recruitment and training

Succession planning focuses on future leadership and statutory posts, and skills/knowledge/experience gaps in critical roles.

There will be a focus on - 

• Understanding what is critical about the role/person
• Who might be able to fill any future gap
• Identifying and developing the support (internal and external) to 'get them there'
• Organising and planning transition into new or expanded roles