The only meaningful difference between DSLR and Mirroless cameras is the viewing system. DSLRs have a mirror that looks through the lens. Mirrorless Cameras have an Electronic Viewfinder (often eye level) that gives you a preview of the photo from a feed from the imaging sensor itself.
Neither is better but Mirrorless is easier to learn on because you get a preview of what the photo will look like including all exposure adjustments.
TEdolph
Agreed that the EVF advantage of Mirrorless (a
'What you see is what you get' exact preview of the image BEFORE you take it) is substantial...but besides this, there are other differences that favour Mirrorless over DSLR including:
1) The numerous features that Mirrorless can offer...my Olympus EM10 ii offers: better video, IBIS, Live Composite, Live Bulb, Focus Stacking, Focus Peaking, AF Track pad, HDR shooting, Black & White shooting, Keystone Compensation, Silent Shutter, etc etc.
2) The overall
sizes of the camera systems, when we account for both camera
and lenses. Mirrorless (especially Micro 43) is markedly smaller and lighter than DSLR.
This makes a significant difference in how likely you are to carry the system with you. An Olympus EM10-II with 14-42mm EZ or a Panasonic GX80/85 with 12-32mm are much more portable than the DSLR equivalent. So mirrorless is great for travel and street photography.
...However, in favour of DSLR, it is better at sports/fast action photography, with its C-AF (continual auto focus tracking) for fast moving subjects.
--
'Photography is not art. It's pressing buttons. People take it up because they can't draw.' Lord Snowdon