A rogue is just a dual-wielding thief, aren’t they? How do they really vary?
D&D 5E has many sub-classes to choose from, spanning several core books. Here are some quick summaries of each subclass, which will give a bit of insight to the theme, generalized game mechanics, and the likely play style to expect. This list isn’t the way you are expected to play the subclass, but my own interpretation of what the subclass archetype is trying to be. Your interpretation may differ, and if it does, please share how!
Theme: Slinking in the shadows, waiting to ambush, and dealing death without even being seen.
Game Mechanics: Skilled with poison, disguise, and dealing damage at the start of combat.
Play-style: You know when to initiate combat, and when to hide if you can’t.
Theme: The prototypical purloiner of other people’s property.
Game Mechanics: More bonus actions, like sleight of hand during combat, and better climbing speed.
Play-style: You like to be crafty with various items and objects, even if they’re not yours.
Arcane Trickster (PHB)
Theme: A magic wielding thief with a penchant for fiddling with things from afar.
Game Mechanics: Limited spell access, with a telekinetic focus (mage hand).
Play-style: You like to interact with the things around you, and poke at danger, all from a safe distance.
Mastermind (Sword Coast Adventurer’s Guide, Xanathar’s Guide to Everything)
Theme: A leader in combat who no one saw coming.
Game Mechanics: Help allies do additional actions, disguise skill, and insight to enemy stats.
Play-style: You’re quick to find enemy weakness and can rally allies to take advantage of your knowledge.
Swashbuckler (Sword Coast Adventurer’s Guide, Xanathar’s Guide to Everything)
Theme: Dealing damage while moving all over the battle map, taunting while you run around.
Game Mechanics: Deal damage, and then disengage without penalty. Also some tank abilities!
Play-style: You hit, and then quickly run out of range. You like the chase, and and know that you can’t be caught.
Inquisitive (Xanathar’s Guide to Everything)
Theme: Incredibly perceptive, with an eye for weakness, treasure, and illusions.
Game Mechanics: Focus on perception abilities, coupled with insightful sneak attacks.
Play-style: You seek out truth, and use that knowledge to your own personal gains, or the defeat of your enemies.
Scout (Xanathar’s Guide to Everything)
Theme: Like the druid, the scout enjoys being wild and untouched. Also known as The Loner Rogue.
Game Mechanics: Moves in response to enemies, and skilled in natural survival.
Play-style: You like being self-sufficient, and you work well without supervision.