Difference between element.isDisplayed() and wait.until(ExpectedConditions.visibilityOf(element));

Question

I am trying to use WebDriver's fluentAPI, and am slightly confused with the choices available. I want to wait for an element to become visible. I undertsand that there are many ways available to do this, but I want to specifically understand the difference between the below two methods :

 (1)new FluentWait<WebElement>(webElement).
            withTimeout(timeoutSeconds, TimeUnit.SECONDS).
            pollingEvery(pollingTime, TimeUnit.MILLISECONDS).
            untilwait.until(ExpectedConditions.visibilityOf(element));

(2) public void waitForWebElementFluently(WebElement webElement) {
    new FluentWait<WebElement>(webElement).
            withTimeout(timeoutSeconds, TimeUnit.SECONDS).
            pollingEvery(pollingTime, TimeUnit.MILLISECONDS).
            until(new Predicate<WebElement>() {
                @Override
                public boolean apply(WebElement element) {
                    return element.isDisplayed();
                }
            }
            );
}

What is the difference between using isDisplayed, and visibilityOf?

Answer 1

isDisplayed :

Is this element displayed or not? This method avoids the problem of having to parse an element's "style" attribute. Source

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visibilityOf

An expectation for checking that an element, known to be present on the DOM of a page, is visible. Visibility means that the element is not only displayed but also has a height and width that is greater than 0. Source.

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So Visibility covers the condition of the element being displayed.