There are 3 different guardian character classes in Destiny 2.
Strengths: Defense, Integrity, Discipline
Disciplined and proud, Titans are capable of both aggressive assaults and stalwart defenses.
This class is best suited for tank players.
Barricade – Forge barriers out of Light to reinforce your fireteam’s position.
Strengths: Agility, Adaption, Instict
Agile and daring, Hunters are quick on their feet and quicker on the draw.
This class is best suited for damage dealers.
Dodge – Avoid incoming enemy attacks with nimble skills.
Strengths: Recovery, Strategy, Arcana
Warlocks weaponize the mysteries of the universe to sustain themselves and devestate their foes.
This class is geared towards magic and is great for support players.
Rift – Summon up planetary energies into columns of Light tat strengthen allies within.
For all subclasses (skill trees), see: Destiny 2 Subclasses & Abilities