The confidence level indicates a degree of certainty (as a percentage) that that the results of a study fall within a given range of values. Typical confidence levels are 95% and 99%.
The confidence interval (margin of error) is a plus-or-minus percentage that is a range within the confidence level. For example, if a 5% confidence interval is used, and 50% of the sample gives a specific answer for a question, the actual result for that question falls between 45% and 55% (50 ± 5).
When using confidence level and confidence interval together, researchers using a 95% confidence level with a ±5% confidence interval can say that they are 95% sure their results are accurate within ±5 percent.