How to identify your melee: duelist vs fighter vs tank
Since not many seem to understand the difference I'm going to help explain. :D
Duelist: Yi, Tryndamere, Fiora, Shaco, Nocturne, Udyr A duelist relies almost ENTIRELY on their auto attacks and will feature multiple attack based stat boosts. Yi gets attack/move speed and on hit true damage. Tryndamere gets critical chance and AD. Fiora gains flat AD and a speed booster that refreshes on kill/assist. Shaco has his clone and initial auto crit. Noc has his stat boosting Duskbringer and spell shield. Udry hits faster by swapping stances and can change between AD nuke+attack speed, movespeed+stun, and lifesteal+shield. Expect a Ghostblade to fit nicely into their hands.
Fighter: Trundle, Vi, Nasus, Jarvan, Mundo, Volibear Fighters still auto attack, but are more tanky and focus less on pure dps. Instead, they like lowering their opponent's stats. Trundle steals AD + armor and mr. Vi reduces armor. Jarvan shreds armor and has an AoE slow. Mundo has a long range skillshot slow, while Volibear has an AoE slow that fears non champions. And they generally build tanky ad items like Maw or reducer items like Omen.
Tank: Alistar, Galio, Maokai, Rammus, Singed, Nautilus Tanks forgo auto attacks almost entirely, instead relying mainly on their abilities. Alistar runs around Pulverizing people, Galio walks into the middle of your team and hits R. Maokai tosses saplings everywhere. Rammus is all about powerballing right into the middle of the enemy team and setting off Tremors next the taunted marksman. Singed just runs about spewing poison everywhere. Nautalis empowers his attacks, but only while his shield is up. Rather than using AD, almost all tanks will want to build AP [ex. Rod of Ages] if they need to increase their damage. (They're basically melee range mages, and are even occasionally used as such. [Ex, AP Cho’Gath])
Feel free to ask about anyone I haven't mentioned.
can be considered duelists as they are pretty good 1v1 though some struggle vs. kiting.
isn't really a great duelist unless fed, he's more of a Teamfight Assassin.
Good duelists almost always have tankiness or lifesteal.
can range from Assassin to Fighter, and his dueling capacity varies greatly based on his build (Hydra vs BOTRK, Ghostblade vs Black Cleaver...)