Mongoose subdocuments vs nested schema

I'm curious as to the pros and cons of using subdocuments vs a deeper layer in my main schema:

var subDoc = new Schema({
  name: String
});

var mainDoc = new Schema({
  names: [subDoc]
});

or

var mainDoc = new Schema({
  names: [{
    name: String
 }]
});

I'm currently using subdocs everywhere but I am wondering primarily about performance or querying issues I might encounter.