The three primary credit bureaus that establish your credit scores are TransUnion, Experian and Equifax. It is not uncommon for all three bureaus to have different scores.For example, your three scores may be a 687, 702 and 679. The reason that these scores differ is because all information on your credit report may not be reporting to all three bureaus, and, therefore, each score model has different inputs off of which to base your score.
Most large accounts will typically be reported to all three bureaus, but some collections may only report to one or two of the three. This is one of many reasons why your scores are different.
When applying for a home loan, most lenders will use your middle score as your representative score. So in the above example, your representative score would be 687 (throw out the highest and lowest score).
You should check your credit bureaus at least once per year. You can do this for free by visiting https://www.annualcreditreport.com/. Credit bureaus are required to provide you with one free credit report per year. Keep in mind that these free reports will not indicate your score (they will try to sell you that), but only the information on your report.
I would not suggest purchasing the credit scores. They are not the true scores that are used when you apply for credit. They disclose that in the fine print. In other words, if you applied for a home loan, and we both pulled your credit at the same exact time, our score will be different than what is reported to you as your consumer score. This is because the act of requesting credit in itself is a different risk factor than someone simply looking at his or her score.
Regardless of the difference in scores, they will both react the same. In other words, if your consumer score goes up, so will your credit score if you are applying for a loan.