Approvals are decisions. The product proposes something (a schema snippet to add, content briefs to write, a change it noticed) and waits. You answer Approve, Needs edits or Reject; the decision is recorded on the business and nothing happens until you do.
Tasks are work only a person can do: build the links this month, fix the crawl error, send the report. Each has a priority (Urgent to Low), a deadline and, when there is one, the document that explains it. Mark them In progress, Blocked or Done. You can add your own tasks too.
Both queues live in the top navigation, with counts. The number on Tasks is the overdue count when anything is overdue, so a red number means "something is late", not "there is a lot".
Tasks are assigned to you by default. Settings → Workspace lets you change what that name is; members you invite can pick tasks up.