In the USA, generally:
4 stripes = Captain
3 stripes = First Officer (copilot)
3 stripes = pilot-rated Flight Engineer(second officer).... (some places: P.F.E's also)
2 stripes = non-pilot Flight Engineer (PFE) ....(& some places: Mechanics also)
1 stripe = non-cockpit types - loadmaster/mechanic/F.A., etc (rare)