Some of the transactions in GL are not in bank statement and vice versa i.e. some trnsactions in bank statement are not posted in GL.

Hey asariaan,

Synchronizing your bank accounts with QuickBooks Online is the best way to keep your account up-to-date. This awesome, time-saving feature makes it easy to enter all you transactions into your books without breaking a sweat. Actively comparing your bank statements with your general ledger is a stellar habit that sets you up for quick reconciliations, as well as accurate sales tax filings. I'll be happy to help you sort this out.

The way bank feeds are managed in QuickBooks Online is by keeping unreviewed bank transactions separate from the rest of your books. These transactions are kept in the For review section of your Banking tab until you add or match them. Once added, these will be posted to your general ledger account. Transactions created manually within your QuickBooks won't appear in your Banking tab, as that section is designed to display your downloaded bank transactions. This handy article includes detailed information regarding this process: Download, match, and categorize your bank transactions in QuickBooks Online

The best way to make sure everything lines up in your accounts is to reconcile regularly. Check out this awesome guide to get started: Reconcile an account in QuickBooks Online

If you find yourself with a large number of unreconciled transactions that you're not sure how to address, your accountant will be able to help. They're your best partner when it comes to reconciliations. You can easily invite your accountant as a user to sort this out together. To find one in your area, simply head to the My Accountant tab in QuickBooks Online then click on Find a pro to help. 

Hope this helps! I've got your back, so let me know if you have any more questions.