What is the difference between Code Smells and Anti Patterns?

Question

I am trying to understand the difference between these two terms. In some contexts that these two terms have been used interchangeably. What is the exact difference between these two terms ?

Answer 1

A Code Smell is something which should be investigated. Is it a piece of delicious cheese or is it rotten beef? An Anti-Pattern is just bad, a Code Smell is something which may or may not be bad.

This quote from the Wiki page is extremely relevant (the emphasis is from the original source):

Note that a CodeSmell is a hint that something might be wrong, not a certainty. A perfectly good idiom may be considered a CodeSmell because it's often misused, or because there's a simpler alternative that works in most cases. Calling something a CodeSmell is not an attack; it's simply a sign that a closer look is warranted.

An Anti-Pattern is a Pattern which, when you follow it, will lead you towards a worse design in the same way that a Pattern will lead you towards a better design:

An AntiPattern is a pattern that tells how to go from a problem to a bad solution. […] In the old days, we used to just call these 'bad ideas'. The new name is much more diplomatic.

Answer 2

I'm writing my answer because I think that the two concepts can be confusing and I want to state a list of clear and direct difference.

Differences

Facts: Anti-patterns "the fact that it looks like a good solution is its essential danger" ¹. On the other side, "smell is by definition something that's quick to spot" and "it's easy for inexperienced people to spot them" ².

The gist: anti-patterns are more abstract, more subtle, more difficult to recognise. Smells are easier and quicker to see or smell.

Facts: Code smells "they are often an indicator of a problem rather than the problem themselves" and "smells don't always indicate a problem" ²

The gist: Code smells are symptoms that could hint to some more profound; anti-patterns are more profound themselves.

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Footnotes:

1. https://martinfowler.com/bliki/AntiPattern.html
2. https://martinfowler.com/bliki/CodeSmell.html

Answer 3

"Code smells" are an insulting judgement of someone's code, based on blindly applying some rule without understanding it. It's a word that is used by some anti-social programmers. NEVER use this word in my presence. You will not be happy.

A "pattern" is something that many people use to solve some kind of problem. An "anti-pattern" is a pattern that doesn't work and gets you into trouble. "Pattern" is often also used to mean "a pattern that works" since things that don't work usually don't become patterns.