Is there any real performance difference between Task.Run and ThreadPool.QueueUserWorkItem in .NET 8, or does Task.Run just wrap it with a Task object?

Task.Run() uses the ThreadPool internally under the hood! The major advantage of Task.Run is that it returns a Task/Task<T> that supports async/await, cancellation tokens, continuation chaining with ContinueWith, and proper exception propagation. QueueUserWorkItem is lower level and harder to capture exceptions from.

Unless you are building an ultra-low-overhead specialized scheduler where the 48-byte Task allocation is unacceptable, always use Task.Run for clean async code.