What are the most important functional differences between C# and VB.NET?

Certainly there's the difference in general syntax, but what other critical distinctions exist? There are some differences, right?

The linked comparisons are very thorough, but as far as the main differences I would note the following:

• C# has anonymous methodsVB has these now, too
• C# has the yield keyword (iterator blocks)VB11 added this
• VB supports implicit late binding (C# has explicit late binding now via the dynamic keyword)
• VB supports XML literals
• VB is case insensitive
• More out-of-the-box code snippets for VB
• More out-of-the-box refactoring tools for C#Visual Studio 2015 now provides the same refactoring tools for both VB and C#.

In general the things MS focuses on for each vary, because the two languages are targeted at very different audiences. This blog post has a good summary of the target audiences. It is probably a good idea to determine which audience you are in, because it will determine what kind of tools you'll get from Microsoft.

This topic has had a lot of face time since .Net 2.0 was released. See this Wikipedia article for a readable summary.