Comment by tankenmate

They are the same only sometimes; devs work on code on feature / fix / whatever branch, then when they've finished dev testing you do a code review and then it gets fast forwarded onto the dev branch, then when it suits for staging (non dev team stakeholder testing / infra testing) it gets fast forwarded to staging, then when it passes staging testing (if necessary), then it get ff onto prod and deployed. so dev will sometimes point to the same commit as staging but sometimes not, and staging will point to the same commit as prod but sometimes not. It's a funnel, a conveyor belt if you will.