What is the difference between a Team Plan and a Solo Plan?
Depending on how you organization or agency is structured you may need multiple users working on various campaigns.
So for example:
You work in a marketing team with 4 other people managing the company's (or client's) social media campaign. In that case you would be considered a team and you can give various team members different levels of access. One person may only deal with one client's Facebook while another team member may be working with your internal LinkedIn Page. You as the administrator would give the permissions accordingly.
You are managing a few clients social media accounts but do it yourself. You might even work on your own small business but you do not have co-workers or interns working with you.
Each plan has multiple levels and you can easily pick the one that is right for you.