Wingmates show up along the top of your hud with name, shield/hull status, and location if wing beacon is enabled. Wings are for realtime combat ops. You can wing-up with anyone. Navlock on a wingmate. See them on your radar in supercruise and normal space (blue icons). Short term membership. Its easy to leave the wing, "leave wing" option or relog.
Squadrons are for more galaxy wide ops and we can chat, see each other in super cruise and normal space (grean icons). Squadrons are more long term membership and you don't get dropped by relog.