How Mirrorless Cameras Compare To DSLRs?

DSLR cameras have new competition on their hands, mirrorless cameras.
Business Insider recently compared the two cameras.
They say the biggest difference
The big difference is how their image sensors and viewfinders work.
Image sensors are the chips inside cameras that use light to capture the photograph. Viewfinders are what photographers look through to compose a shot.
Mirrorless camera's have an advantage, because they don't use battery life as much.