How does closure works over this piece of express node js code?

Question

Here I had created mongoose model name Tour. I am not able to get how is try/clause can be removed by refactoring the code?Can anyone please help me to understand how is both the code same!

const createTour = async (req, res) => {
  try {
    const tour = await Tour.create(req.body)
    res.status(201).json({
      status: 'Success',
      data: {
        tour,
      },
    })
  } catch (err) {
    res.status(400).json({
      status: 'fail',
      message: err,
    })
  }
}

Later refactored code is as below -

const catchAsync = function (fn) {
  const inner = function (req, res, next) {
    return fn(req, res, next).catch(next)
  }
  return inner
}

const createTour = catchAsync(async (req, res) => {
  const tour = await Tour.create(req.body)
  res.status(201).json({
    status: 'Success',
    data: {
      tour,
    },
  })
})

I am not abled to understand why both code are working same?