StringWriter or StringBuilder

Question

What is the difference between StringWriter and StringBuilder and when should I use one or the other?

Answer 1

Building on the previous (good) answers, StringWriter is actually much more versatile than StringBuilder, providing lots of overloads.

For example:

While Stringbuilder only accepts a string or nothing for Appendline

StringBuilder sb = new StringBuilder();
sb.AppendLine("A string");

StringWriter can take a string format directly

StringWriter sw = new StringWriter();
sw.WriteLine("A formatted string {0}", DateTime.Now);

With StringBuilder one must do this (or use string.Format, or $"")

sb.AppendFormat("A formatted string {0}", DateTime.Now);
sb.AppendLine();

Not do or die stuff, but still a difference