Don't get me wrong, there are a lot of other roles where you lead tech teams, animate the delivery, mentor engineers.
The difference is that people management becomes part of your responsibilities when you are an EM.
It's actually your very first mission.
Your mission is to lead, and support a team of engineers to maximize their positive impact on the expected business outcomes.
Individual and team management is the cornerstone of this role. That's what makes the transition tricky, it requires an important shift in your focus, and it requires training new muscles.
By extension, the mission will also include responsibilities for the team's delivery, guiding the team, its cross-functional communication, and its alignment with the company's strategy.