What is diiference in purchase bill and expenses

Thanks for dropping by the Community, @anubhiindia-gmai.

I have some information about the difference between the purchase bill and expenses. You use "Bill" to keep track of your committed costs by knowing all your Accounts Payable. The "Expense" is done and paid for in one shot. You can create these transactions (a bill, bill payment, expense, and purchase order) by following these steps below.

1. +New at the top left of your screen. 
2. Select Bill, Pay Bills, Expense, and Purchase order under Vendors.
3. Enter the details of each transaction.
4. Click Save and close. 

After you send a purchase order (PO) to your supplier and make a payment, you can link it by creating a bill and bill payment. Need more details? Check out this link.

If you need help with other supplier tasks, please visit our QuickBooks Online page to go our general supplier's topic with articles.

Fill me in if you still have questions or concerns. Just drop them in the reply section below. I'm more than willing to answer them for you. Have a great weekend ahead.