What is the difference between [AcceptVerbs(HttpVerbs.Post)] and [HttpPost]?

I can decorate an action either with the [AcceptVerbs(HttpVerbs.Post)]/[AcceptVerbs(HttpVerbs.Get)]

[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Create(string title)
{
    // Do Something...
}

or with the [HttpPost]/[HttpGet] attributes

[HttpPost]
public ActionResult Create(string title)
{
    // Do Something...
}

Are they different?

[HttpPost] is shorthand for [AcceptVerbs(HttpVerbs.Post)]. The only difference is that you can't use [HttpGet, HttpPost] (and similar) together on the same action. If you want an action to respond to both GETs and POSTs, you must use [AcceptVerbs(HttpVerbs.Get | HttpVerbs.Post)].

Nothing. One is just shorthand for the other.