MongoDb: Difference between $push/$addtoset

Question

I read the documentation in the MongoDb and I used a simple proves and I only look that: Push is sorting the array but addtoSet isn\'t it.

For me visual

Answer 1

$addToSet and $push does the same thing, however $push just pushes any item disregarding the duplication causing redundancy. The former pushes only unique items, no duplication.