What is the difference between connectionstrings and appsettings?

There is a fundamental difference between connectionString and appSettings:

They look for different things. In .NET 2.0 and above:

A connectionString object is an XML node that has specific attributes to set; and semantically it refers to a database connection string.

For instance, a connectionString looks like the following:

<connectionStrings>
    <clear/>
    <add name="LocalSqlServer"
          connectionString="Data Source=(local);Initial Catalog=aspnetdb;Integrated Security=True"
          providerName="System.Data.SqlClient" />
  </connectionStrings>

You'll notice it has a few different attributes:

• name
• connectionString : This has a specific string inside of it, it needs an Initial Catalog, a security mechanism (in this case Integrated Security
• providerName

Whereas appSettings is just a user-defined Key-value pair that allows you to... well... set application settings. It can be anything:

<appSettings>
    <add key="Mom" value="Your"/>
    <add key="UseCache" value="True"/>
    <add key="MapsKey" value="1234567890-AA"/>
    <add key="SMTPServer" value="smtp.peterkellner.net"/>
</appSettings>

In many cases, it would just be odd to put the connectionString in a key-value pair like appSettings (semantically and programmatically). As well as it would make it more difficult to encrypt the connectionString when you need to.

There is more information about this from this blog post.

As far as I know it doesn't make a huge amount of difference, other than it being in the "correct" place - the main advantage of putting connection strings in their own section (you do encrypt your connection strings.. right?) is so you can encrypt that section without encrypting all of the settings you might want to change.