Is using unique_lock in new scope equivalent to unlock call at the end of work with shared resource?

I have seen a lot of examples of code when developer uses std::unique_lock in new scope for automatically unlocking mutex:

...
// do some staff
{
  std::unique_lock<std::mutex> lock(shared_resource_mutex);
  // do some actions with shared resource
}
// do some staff
...

In my opinion it would be better to implement this behaviour using method unlock from std::unique_lock API in this way:

...
// do some actions
std::unique_lock<std::mutex> lock(shared_resourse_mutex);
// do some actions with shared resource
lock.unlock();
// do some actions
...

Are these two fragments of code equivalent? For what purpose developers use the first variant? Maybe to emphasize (using parentheses) code that can not be executed parallel?