Is a DO a real doctor?

Most people learnt that Dr Conley (centre) was a DO, rather than an MD, when he entered the limelight after Trump got Covid-19. — TNS

What is the difference between a doctor of medicine (an MD) and a doctor of osteopathic medicine (a DO)?

It’s a question many Americans may be asking after learning that White House physician Dr Sean Conley, who is in charge of US President Donald Trump’s healthcare, is a DO and not an MD.