What is the difference between ChromeOptions and DesiredCapabilities?

ChromeOptions is a class that can be used to manipulate capabilities specific to ChromeDriver. For instance, you can disable Chrome extensions with:

ChromeOptions options = new ChromeOptions()
options.addArgument(“disable-extensions”);
ChromeDriver driver = new ChromeDriver(options);

DesiredCapabilities can also be used to manipulate a ChromeDriver session. To change individual web driver properties, DesiredCapabilities class provides key-value pairs.

But, ChromeOptions supports limited clients whereas DesiredCapabilities supports a vast number of clients. ChromeOptions is supported by Java and other languages. DesiredCapabilities is available in Java, but its use is deprecated. When working with a client library, like Selenium Ruby Client, the ChromeOption class will not be available and DesiredCapabilities will have to be used.

DesiredCapabilities are commonly used with Selenium Grid, for parallel execution of test cases on different browsers. However, one can use both DesiredCapabilities and ChromeOptions using merge:

DesiredCapabilities capabilities = new DesiredCapabilities();
options = new ChromeOptions();
options.merge(capabilities);
driver = new ChromeDriver(options);