Answer
$push adds an element to an array even if it already exists. $addToSet adds it only if it is not present, preventing duplicates.
Quick Answer
$push appends a value to an array even if it already exists - can create duplicates. $addToSet adds a value only if it doesn't already exist in the array - like a set in math. Use $addToSet when maintaining unique values (tags, categories, user IDs). Use $push when order matters or duplicates are allowed (event log entries).
S
SugharaIQ Editorial Team
Verified Answer
This answer has been peer-reviewed by industry experts holding senior engineering roles to ensure technical accuracy and relevance for modern interview standards.
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Source: SugharaIQ