both these are quite similar in features.. But Nikon has a few advantages over the Canon and is the better performer.
The image sensor is a bit larger and Max ISO and better low light performance.
About mirrorless - posted by myself on a different thread copied below.
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The main difference in a mirrorless camera against a standard DSLR is that the mirrorless one is smaller with simpler construction. No mirror/prism - reduces the size, the light falls directly on the image sensor.
The AF speed was a drawback in the earlier versions of DSLM cameras - as they used contrast detection which was slower than the phase detection used in the DSLR. But the modern range of DSLMs have overcome this issue and uses hybrid phase/contrast detection and it is no longer a problem.
Video quality of the DSLM is supposedly better and if you can afford a DSLM is a good choice.
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