Yoga 920 or Yoga c930? UHD or FHD?

I'm looking to replace a Macbook Pro Retina 2013 right now. The primary purpose is notetaking and student work.

1. Will getting a Yoga with FHD be a bad enough downgrade from retina display to warrant getting a UHD?
2. Is a Lenovo Yoga 920 8gb UHD offered, or is it strongly recommended/necessary to have 16gb with UHD?
3. How do I figure out if the c930 is worth it? I know the battery life is an hour shorter than the 920. I feel like the rest comes down to little details, but the difference is only $50. Which is better for my purpose?

Thanks