type

Interfaces can't express unions, mapped types, or conditional types.

• Type aliases can express any type.

interface

interface is always in object shape, not primitives.

• interfaces can use extends to inherit from another interface.

It's a good rule of thumb to think of using interface when you consciously need extends.

When to use what

You should use types by default unless you need a specific feature of interfaces.

• you can technically blend and use type and interface together,

interface over type when type extension is involved

When you're working with objects that inherit from each other, use interfaces.

• extends makes TypeScript's type checker run slightly faster than using &.

// extending interface
interface IShrimpFriedRice extends IFriedRice {
  ingredients: IShrimp,
}

// extending type
type Latte = {
  liquid: Coffee
} & Milk