The original is £100 cheaper, not sure of what the difference is to the Mk2 though.
If it has all you need it would seem a good, well reviewed, buy.
EDIT: Just found this:-
"So what's new in the 2020 update? A fair bit actually, according to
Technics. To start with, the SC-C70MK2 is equipped with a newly-developed 8cm woofer unit which now includes a slimmed-down voice coil, enhanced airflow and a more rigid diaphragm. Then, there's a new hi-res ready 2cm dome tweeter unit featuring a lighter silk diaphragm. The levelled-up tweeter is combined with an acoustic lens, the shape of which has been optimised to deliver more expansive sound."
It also would appear that the original needed improving in the bass department,,,