Buffer currently supports scheduling across multiple social channels, shared calendars, team roles, draft approvals, comments or notes, and publishing workflows. For a team whose main problem is planning and distributing ready-to-publish posts, that is a strong fit.
Somea is aimed at a different upstream problem: the team already owns a growing visual archive, but finding a suitable asset, understanding what can be reused, and carrying that source into a reviewed social direction is the expensive part. Somea can then connect the reviewed work toward scheduling and publishing where configured.
That means the products may overlap around review and publishing, but they do not begin from the same core job. A fair decision should start with the point in the workflow that currently consumes the most time or creates the most dropped context.