The three major credit bureaus use similar information sources, such as banks, credit card issuers, and department stores, which report to them
electronically.  But they also have different sources, which won't show up with each credit bureau.
Example:  A few years ago, I bought a rental house where the property taxes were supposed to be paid by the escrow holder (because the tax bill was
coming due a week or two after my purchase date).  Somehow, the escrow holder failed to pay the property taxes on time.  The taxes were paid many months late.  One of the credit bureaus picked up that late payment from the local tax collector's office and reported it on my credit report.  The other two credit bureaus didn't include it.  But I had a heck of a time getting it off that one credit report, even though it wasn't my fault the tax payment was late, as I patiently explained over and over to the impersonal credit bureau.
Don't give up.  Persistence pays when it comes to getting your credit report corrected, thus resulting in an improved FICO score.
Credit bureaus often include on your credit report unpaid debts, which
become a matter of public record.  They frequently pick up unpaid judgment liens, mechanics' liens, federal and state income tax liens, lawsuits, etc.
Bankruptcies stay on your credit report for 10 years.  Other credit information usually remains on your credit report up to seven years, whether the
information is good or bad.  However, if you have re-established credit as
recently as 24 months after discharge from bankruptcy, you'll probably be able to get home loan approval.  Fannie Mae even has a brand new program for "sub prime" home loan lending so more mortgage applicants can be
approved.
Avoid too many inquiries on your credit reports.  If you're shopping for a home loan, don't also apply for credit cards, auto loans, and other credit.  Wait until after your home loan is approved and successfully closed. 
Unfortunately, if you have too many recent inquiries on your credit reports within the last six months, the number of inquiries can hurt your FICO score. The folks at Fair, Isaac and Co. in Novato, Calif., say their program is
supposed to consider most applicants for home loans (and auto loans) who often apply at more than one source so several inquiries within a two-week
period are not supposed to adversely hurt FICO scores.
If any lender made an unauthorized inquiry without your permission, you are entitled to have it removed by the credit bureau.  However, when a credit
issuer buys a list of good credit risks from a credit bureau, that is not
considered an inquiry (although it will show up on your credit report--that's how those weird credit card issuers you've never heard of get your name to mail unsolicited letters saying "Congratulations.  You're pre-qualified for one of our credit cards").

How to get pre-approved for a home loan:
By the way, "pre-qualified" for a home or auto loan or a credit card means
absolutely nothing!  When a lender says you're pre-qualified, that means, "We think we might decide to grant you credit."  However, if a lender says you're "pre-approved," that means the lender will grant you credit or a loan, often subject to limitations such as an appraisal of the home purchased and
reverification of your income and credit.  If a real estate agent or a home builder says you are pre-qualified or pre-approved for a home loan that means nothing unless that individual also has mortgage loan approval authority. Don't be tricked.
Before shopping for a home, shop for a mortgage.  Even if you have "less than perfect credit," in today's home loan marketplace, you can probably get a home loan.  Of course, if you have a very low FICO score, you'll probably pay a higher than normal interest rate.  But that's better than not buying a home! Shop around.  Thankfully, not all mortgage lenders are the same.