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 our own interpretation of what the subclass archetype is trying to be. Your interpretation may differ, and if it does, please share how!
Circle of the Land (PHB)
Theme: Drawing magic from nature itself, the land druid connects to the environment as an agent of the wild.
Game Mechanics: Starts with an extra cantrip and choosing a type of environment to theme your spell choices. With an ability to regain spell slots, you’ll be able to focus more on spells. At later levels, the land druid is much more difficult to entangle and can ignore difficult terrain. At higher levels, they become immune to poison disease, cannot be charmed by fey or elementals, and can also have an innate sanctuary ability, making attackers have to divert attacks elsewhere.
Play-style: You’d rather focus on the utility spellcasting than the wild-shape. It’s like playing the ranger, but with a lot more focus on spellcasting.
Circle of the Moon (PHB)
Theme: Weaving the power of the wild beasts in nature, the moon druid uses the skills and abilities of nature’s denizens.
Game Mechanics: Able to wild-shape more quickly, using it as a bonus action, and with higher limitations than usual. Later on, able to make magical strikes in wild-shape. At 10th level, the moon druid can turn into elemental forms. At their highest level, they can use the alter self spell at will, making it even easier to shape-change as you want.
Play-style: You love the idea of shape-changing and want to focus on the wild-shape ability with additional elemental choices.
Circle of Dreams (XGE)
Theme: Nature’s nurturing agent, the dream druid focuses on the mystical and mysterious elements.
Game Mechanics: Starts off with additional ability to heal. Later on, you gain an ability to summon a very comforting and relaxing hearth for a short and long rests. While in this hearth, you’ll be invisible and gain some additional skill bonuses. Also gains the ability to teleport as a bonus action. At their highest level, the dream druid can cast spells during rests, like scrying and teleportation, but can teleport – for free – to the last place you rested.
Play-style: You like the druid, but want to have more healing options available, and want to have some awe inspiring abilities to use outside of combat.
Circle of the Shepherd (XGE)
Theme: Embraces that they, as a human, are also an animal in nature, working with and allying themselves to the animals of the wild.
Game Mechanics: Starts off with additional ways to speak and commune with nature. Can also summon a totem, which can be different upon summoning, granting different kinds of bonuses (such as hit points, strength, attack advantage, perception, better healing abilities, etc). Later on, focus more on being able to summon stronger allies, and apply extra healing abilities to your totem. At the highest level, if the shepherd druid is knocked unconscious, it will summon animals to support and protect them until help can come.
Play-style: You want to focus on the summoning abilities that the druid gets. The wild-shape vs. spells decisions seems tough, so you’d like to get abilities that can focus on both.
Circle of Spores (GGR)
Theme: Where most have a passion for the environment or it’s denizens, the spore druid appreciates the life that is hardest to see: the bacterial and fungal.
Game Mechanics: Starts off able to summon spores to help deal damage and protect, giving additional melee damage and causing damage to those who attack you. Later on, able to animate a recently dead creature, giving it new life, as an ally of yours. At highest levels, able to use the spores ability in a larger area of effect, and gain many protecting abilities, like being immune to blindness, deafness, poison, fright, and critical hits.
Play-style: You want to show the powerful force of nature, persisting through death, seeing nature magic as always an option.