You Should Seek Out a Lender's (Pre-)Approval, Too

  There’s a world of difference between being pre-qualified for a loan and being pre-approved. Pre-approval means you’ve got skin in the game. It means you’re a boss. And it's proof that you can buy.
Besides being the grown-up thing to do, pre-approval puts you in a better position when you make an offer. Everyone takes you more seriously. Pre-approval also provides evidence to your real estate professional and the seller (or seller’s agent) that a trusted financial institution is willing to finance the purchase.
In most housing markets, sellers are going to expect you to be pre-approved when you make your offer. And when you’re pre-approved, you’re more likely to have your offer accepted — or at least, you won’t lose out on a bid because you have to go back to the bank to get approved for a loan.
As for pre-qualification, it’s an approximation and not necessary unless you have no clue about your creditworthiness and just want a snapshot.
  By contrast, with a pre-approval, a lender typically goes deeper and tells you more specifically how big a loan you can get. Caution here: Just because the lender says you can take out a loan for an amount, doesn't mean you should! Consider your lifestyle and monthly budget to decide on the responsible loan amount for you. 

  To get pre-approved, you must also authorize a lender to pull your credit. 

• Borrowers with credit scores of 760 or higher can typically qualify for the lowest interest rates. 
• Borrowers with credit scores below 650 may need to apply for a non-conventional mortgage, such as a Federal Housing Administration (FHA) loan — a government-backed loan that requires a minimum credit score of 580 but lets borrowers make as low as a 3.5% down payment.
• Borrowers with credit scores below 580 can still qualify for FHA loans in some cases, but they may have to make at least a 10% down payment. The lower the score, the tighter the requirements become.

  When you’re pre-approved, you’ll receive a Loan Estimate. This three-page document is about to be your new best friend. Call us to walk you through this process!

Source: 
https://www.houselogic.com/buy/how-to-buy-step-by-step/types-of-mortgage-lenders