The Content Lead guides the substance of the course and acts as a champion for the material. This person (and it's exactly one person for a given course) is responsible for the content and empowered to direct its final form. Typical activities include:
Setting the course outline and structure
Ensuring the course covers its learning objectives in a manner suitable for its intended audience
Participating in all content meetings
Reviewing and guiding content at every step, from outline through final acceptance
Acting as the final decisionmaker on matters of substance
While Content Leads are responsible for the final product, they don't typically do all the work. They're supported by colleagues, peers, and a production team.
Content Team Members
Most courses have one or more Content Team members assigned. The Content Team takes an active role in the work, typically:
Helping to author the course outline, define the substance
Reviewing scripts, drafts
Participating in all content meetings
Sourcing relevant material, examples, links
Content Team members are typically selected for their knowledge and field experience.
SMEs
Most courses have one or more SMEs attached. The SME is role on the project is an expert reviewer, advising the team on matters of substance and technical correctness.
Some Content Team members may have an SME level of experience — the primary differentiation is that the Content Team members are active and frequently engaged on every steps of the content creation, while the SME role is primarily as a reviewer at key points.
Reviewers
Most courses have one or more reviewers. These are people who are not active creators of the content, and not necessarily subject experts, but who have some perspective. This is also the assigned role for anyone who needs to approve the content – but isn't in any other role.
Production Team
The production team shepherds the production process, arranges meetings, does non-substantive editing, and similar.