Marco > King so the events of the most recent chapter i.e. Zoro finally defeating King ('regular' YC1-level) extreme diff doesn't really have any bearing on Zoro vs. Marco beyond Zoro now simply giving Marco more difficulty at most.
Zoro needed AdCoC and Enma buffs to meaningfully damage King, while
exhausted Marco's knee strike made defense mode King bleed.
That's quite an impressive feat looking back considering some people were hyping King's durability as >=Kaido's (dragon form at least) and disparaging Marco's AP
I'm still yet to see how Zoro can meaningfully deal with Marco's regeneration while Marco, apart from his regen, retroactively has great AP as evidenced by him making defense mode King bleed with a casual knee and earlier in the fight he has a smaller but noteworthy feat in making Queen cough up blood from his Pheonix Brand attack.
I'm sure when Zoro finally masters Enma he would surpass Marco tho but as of now it's still Marco high/extreme diff imo.