What is the difference between [Document,Document] and [{},{}] with meteorjs?

Question

const sample1 = useTracker(() => {
  // …   
  return Collection1.find({}).fetch() 
})

console.log(sample1) 
// [Document,Document] 
// 0:Document {_id:’1223123’, name:’sample’}
// 1:Document {_id:’1211111’, name:’sample2’}

const sample2 = useTracker(() => {
  // …   
  return Collection2.find({}).fetch() 
})

console.log(sample2) 
// [{},{}]
// 0: {_id:’456456’, name:’sample’}
// 1: {_id:’654654’, name:’sample2’}

I’m using useTracker and what is the difference between [Document, Document] and [{},{}]?

Both are getting documents but sample1 has Document letter and sample2 doesn't.