I have this piece of code

const baseSchema = Joi.object.keys({
   name: Joi.string().required()
})

Now I want to add more keys to this schema, I can write

const basicInfoSchema = baseSchema.keys({
   address: Joi.string().required(),
   phoneNumber: Joi.number().required()
})

or

const basicInfoSchema = baseSchema.append({
   address: Joi.string().required(),
   phoneNumber: Joi.number().required()
})

What's the difference between the two?