In the 401(K) statement that has given by Employer, what is the difference b/w closing price and vested balance?

Depending on the specifics of your company's plan, they may have a vesting schedule that makes the company contributions (and earnings on those contributions) yours only if you are employed by them a certain length of time. For example - a typical plan has a vesting schedule of 20% at the year 2 anniversary, 40% at year 3, 60% at year 4, 80% at year 5 and 100% at year 6. So under this example if your tenure is less than 6 years your vested balance will be less than the account balance.

"Closing price" refers to the market value of the stocks, mutual funds, or whatever the account is invested in as of the date of the statement.