The Treasure Hunter subclass is called a Speciality.

Burglar

Burglar is the physical infiltration specialist.

Clever-Handed allows the bonus action from Cunning Action to make a Sleight of Hand check or take the Use an Object action.

Tree-Climber removes the normal extra movement cost of climbing and improves climbing and jumping through Dexterity.

At 7th level, Quiet-Footed grants advantage on Stealth and Sleight of Hand checks when the Burglar moves no more than half speed on the same turn.

Choose Burglar for locks, ruins, climbing, stealth, and manipulating objects under pressure.

Spy

Spy is the observation and intelligence specialist.

Cunning Eye adds Intelligence to qualifying Insight and Perception checks and adds Search to Cunning Action.

Weak Spot allows the Spy to study a creature with Investigation or Perception opposed by the target's Stealth. Success creates a personal Sneak Attack route against that target under the feature's restrictions.

At 7th level, Sharp-Eyed grants advantage on Investigation and Perception checks when moving no more than half speed.

Choose Spy for surveillance, detecting deception, identifying targets, and reconnaissance.

Choosing between them

Burglar → infiltration, climbing, objects, stealth Spy → observation, Search, investigation, target analysis