President Joe Biden and his predecessor Donald Trump both sent social media posts to their millions of followers on Christmas Day, but their messages were starkly different. While Biden sent more traditional festive greetings and well wishes from him and the first lady on Christmas Day, Trump instead spent December 25 airing a number of grievances, continuing to post false claims about the 2020 election, and even call the U.S. a "failing nation." In a tweet from his personal account, Biden tweeted a message of love and unity, as one might expect from a president, on Christmas Day. "Jill and…