Dont worry one bit about the difference between the two plants. All that is is different phenos. In many ways they may as well be different strains. Just enjoy watching the difference between the two.
Yellowing of lower leaves will be a macro nutrient issue. Sounds like N but could be a touch of mag or even K if there's spots or burnt edges. Hard to tell without a photo.
N deficiency in late flower is normal as I'm sure you've read. The extent is what you want to worry about. Biobizz is often said to be short of N in Bloom. You could up that just slightly but it really might not be necessary. You're in week 8 so very almost there. 2-3 weeks left. The plant will start to lose leaves but probably has everything it needs to finish. Next time you could keep the grow nutes going for longer.
Probably a good time to start introducing overdrive now. I've never used it but the buds are at the stage where they're about to start bulking up so will want lots of K.
Goods work though mate. You really are on the home stretch. Pretty guaranteed to finish well now.
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