Mongoose 'static' methods vs. 'instance' methods

I believe this question is similar to this one but the terminology is different. From the Mongoose 4 documentation:

We may also define our own custom document instance methods too.

// define a schema
var animalSchema = new Schema({ name: String, type: String });

// assign a function to the "methods" object of our animalSchema
animalSchema.methods.findSimilarTypes = function (cb) {
  return this.model('Animal').find({ type: this.type }, cb);
}

Now all of our animal instances have a findSimilarTypes method available to it.

And then:

Adding static methods to a Model is simple as well. Continuing with our animalSchema:

// assign a function to the "statics" object of our animalSchema
animalSchema.statics.findByName = function (name, cb) {
  return this.find({ name: new RegExp(name, 'i') }, cb);
}

var Animal = mongoose.model('Animal', animalSchema);
Animal.findByName('fido', function (err, animals) {
  console.log(animals);
});

It seems with static methods each of the animal instances would have the findByName method available to it as well. What are the statics and methods objects in a Schema? What is the difference and why would I use one over the other?