So basically, new hires and mostly everyone else is a TM or Team member. Team Leads are just a little bit higher than that. ETLs are Executive team leaders, they're in charge of departments essentially (electronics, AP, hardlines, etc.) and lower volume stores they probably double up.
All you need to know is that LOD (Leader on duty) is a rotating position among ETLs. Call GSTL (Guest service team leader) for cashier/register-related problems and call LOD for everything else. Ask the TMs around you first though, if your question is kind of stupid. Honestly, I know the leadership in my store by name, not position. if you call for LOD, whoever answers that call is the LOD. not much else really affects your job on the salesfloor.
Coming from a quasi-military background, the chain of command matters but it's not that rigid at target. Try to solve your problem as low on the totem pole as possible (ie dont involve the store manager or other department's etls). Just figure out who is directly above you and work from there