What is the difference between Task.Run(), Task.Factory.StartNew() and Thread?

Question

Ponu Maurya · Answer

In C#, Task.Run(), Task.Factory.StartNew(), and 
Thread all execute code concurrently, but they differ in 
abstraction level, use case, and behavior. Understanding these differences helps you choose the right tool for the job.
1. Thread – Low-Level Threading
Represents a physical OS thread.Must be manually started.Gives full control over thread lifetime.Expensive in terms of memory and CPU.
Example:
Thread thread = new Thread(() =andgt; DoWork());
thread.Start();
Use When:
You need long-running, dedicated threads.You require thread-level control (e.g., priority, abortion).
2. Task.Run() – Simplified Task-Based Concurrency
Queues the task to the ThreadPool.High-level wrapper for asynchronous, parallel execution.Optimized for CPU-bound or background work.Returns a Task you can await.
Example:
await Task.Run(() =andgt; DoWork());
Use When:
You want to run code asynchronously without blocking.You're doing short, CPU-bound operations in the background.
3. Task.Factory.StartNew() – Advanced Task Creation
Offers fine-grained control over task scheduling.You can specify TaskCreationOptions, TaskScheduler, etc.Less recommended since Task.Run() was introduced in .NET 4.5.
Example:
Task.Factory.StartNew(() =andgt; DoWork(), 
                      CancellationToken.None, 
                      TaskCreationOptions.DenyChildAttach, 
                      TaskScheduler.Default);
Use When:
You need control over task options, scheduling, or
child tasks.
Key Differences Table
Feature
Thread
Task.Run()
Task.Factory.StartNew()
Abstraction Level
Low
High
Mid
Returns a Task?
No
Yes
Yes
ThreadPool usage
No (dedicated thread)
Yes
Yes (by default)
Control over scheduling
Yes
Minimal
Full
Best for
Long-running background work
Short CPU-bound work
Advanced scheduling needs
Supports await
No
Yes
Yes
Memory cost
High
Low
Low
Recommendations:
Use Task.Run() for most async or background work in modern apps.Avoid Task.Factory.StartNew() unless you need advanced options.Use Thread only when:
You need full control over the thread lifecycle.You are building infrastructure like a custom thread pool.
Also Read
What is the lock keyword in C#? Why is it needed?What is the difference between shallow copy and deep copy?

forum

What is the difference between Task.Run(), Task.Factory.StartNew() and Thread?

Anubhav Kumar

Can you answer this question?

1 Answers

1. `Thread` – Low-Level Threading

Example:

Use When:

2. `Task.Run()` – Simplified Task-Based Concurrency

Example:

Use When:

3. `Task.Factory.StartNew()` – Advanced Task Creation

Example:

Use When:

Key Differences Table

Recommendations:

Liked By

Feature	`Thread`	`Task.Run()`	`Task.Factory.StartNew()`
Abstraction Level	Low	High	Mid
Returns a `Task`?	No	Yes	Yes
ThreadPool usage	No (dedicated thread)	Yes	Yes (by default)
Control over scheduling	Yes	Minimal	Full
Best for	Long-running background work	Short CPU-bound work	Advanced scheduling needs
Supports `await`	No	Yes	Yes
Memory cost	High	Low	Low