The question bank is your reusable, organization-wide library of interview questions. Write a question once and attach it to as many jobs as you like. Each question has a maximum answer duration, capped by an organization-wide limit.
Groups are named sets of questions, handy when you reuse the same battery of questions for similar roles. You can search the bank by question text or by tag, and filter by tag, to find the right question quickly.
Remember that attaching a question to a job snapshots it, so refining a question in the bank later never disturbs a job already in progress.