'Difference between aggregate and find with map mongodb

I tried to run this code to know the response time between aggregate and a simple find with .map() javascript function .

console.time("time 1")
Models.Student.aggregate([
{
   $lookup:
   {
       from: "schools",
       localField: "School",
       foreignField: "_id",
       as: "school"
   }
},{$match:{'school.name':"my favourite school"}}]).then(students=>{
  console.timeEnd("time 1")


})


console.time("time 2")
Models.Student.find().populate({path:'School',match:{name:"my favourite school"}}).then(students=>{
  students=students.filter(student=>student.School)
  console.timeEnd("time 2")

})

And i got this result of time for both codes :

time 2: 24.131s
time 1: 44.981s

Can someone tell me please why would we use aggregate when it needs twice of the needed time by the simple find and map.

node.jsmongodbmongoose


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