When you make a false statement with a deliberate intent to deceive, that is an intentional untruth or falsehood, we label it a lie. 

When you innocently make a false statement you might still be considered a liar as the listener cannot accurately determine intent.  You might be perceived as acting deliberately by default.

The lie you believe is the truth you tell

Making mistakes relative to the veracity of the information you share with others, however innocent, can result in serious negative impacts.

If a statement you make is unknowingly false, it could still be perceived by others as a lie.  While intent matters relative to the determination of a lie or a mistake, the intent is not always easy to determine.

Be Honest

Errors that could be taken as lies should be acknowledged, apologized for and rationale supporting the innocence of the intent.  This disclosure should be undertaken as soon as the mistake is revealed.

Defending your actions is usually not a good idea.  This can reinforce the perception of dishonesty.  Straight up agreement with your accuser and appropriate remorse always works best.

Sometimes you may have lied for the better good.  If uncovered the same approach is best, acknowledge and apologize.  Justifying your lack of veracity might make you feel good but usually does not work well with others.

Accuracy Matters

Avoiding factual mistakes is always the best approach though.  Acknowledge and apologize can work to minimize negative consequences surrounding communication of inaccuracies but it’s best to not put yourself in that situation.