FICO and VantageScore are two different companies that provide credit scores to consumers and lenders. The scores are similar in that they look at your credit history and based on specific factors like payment history, length of your open credit lines, types of credit accounts, etc., provide a score.
The two companies weigh the factors slightly differently, so your score could differ slightly. Regardless of the score model, taking steps to improve one credit score will generally result in improvement to both.