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    <p>One big difference is that <code>Enumeration</code>s come with support for instantiating them from some <code>name</code> String. For example:</p> <pre><code>object Currency extends Enumeration { val GBP = Value("GBP") val EUR = Value("EUR") //etc. } </code></pre> <p>Then you can do:</p> <pre><code>val ccy = Currency.withName("EUR") </code></pre> <p>This is useful when wishing to persist enumerations (for example, to a database) or create them from data residing in files. However, I find in general that enumerations are a bit clumsy in Scala and have the feel of an awkward add-on, so I now tend to use <code>case object</code>s. A <code>case object</code> is more flexible than an enum:</p> <pre><code>sealed trait Currency { def name: String } case object EUR extends Currency { val name = "EUR" } //etc. case class UnknownCurrency(name: String) extends Currency </code></pre> <p>So now I have the advantage of...</p> <pre><code>trade.ccy match { case EUR =&gt; case UnknownCurrency(code) =&gt; } </code></pre> <p>As <a href="https://stackoverflow.com/users/501113/chaotic3quilibrium">@chaotic3quilibrium</a> pointed out (with some corrections to ease reading):</p> <blockquote> <p>Regarding "UnknownCurrency(code)" pattern, there are other ways to handle not finding a currency code string than "breaking" the closed set nature of the <code>Currency</code> type. <code>UnknownCurrency</code> being of type <code>Currency</code> can now sneak into other parts of an API.</p> <p>It's advisable to push that case outside <code>Enumeration</code> and make the client deal with an <code>Option[Currency]</code> type that would clearly indicate there is really a matching problem and "encourage" the user of the API to sort it out him/herself.</p> </blockquote> <p>To follow up on the other answers here, the main drawbacks of <code>case object</code>s over <code>Enumeration</code>s are:</p> <ol> <li><p><em>Can't iterate over all instances of the "enumeration"</em>. This is certainly the case, but I've found it extremely rare in practice that this is required.</p></li> <li><p><em>Can't instantiate easily from persisted value</em>. This is also true but, except in the case of huge enumerations (for example, all currencies), this doesn't present a huge overhead.</p></li> </ol>
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    1. COThe other difference is that Enumeration enum is ordered out of the box, whereas case object based enum obviosly not
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    2. COAnother point for case objects is if you care about java interoperability. The Enumeration would return the values as Enumeration.Value, thus 1) requiring scala-library, 2) losing the actual type information.
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