Hi Sophia -- Thanks for your question. Did you see our response to your other question here:

https://www.goodbed.com/mattress-questions/9294/question-re-comfort-on-the-beautyrest-black-k-class-ultraplush-pillowtop/

If you haven't already done so, I'd recommend checking out our overview of the current Beautyrest Black line-up, which you can find here:

https://www.goodbed.com/reviews/beautyrest-black-mattress-preview/

This provides an overview of how the C-Class and K-Class differ in their general features and construction.

In terms of how the feel of the K-Class Ultra Plush Pillow Top model compares to the C-Class Plush Pillow Top, they are very similar overall. That said, here are some slight differences:

• The K-Class is a tad softer, though both fall into the "Very Soft" category on our softness spectrum
• The K-Class has deeper cushioning -- "Extra-Deep" for the K-Class vs. "Deep" for the C-Class. The deeper the cushioning, the more it provides the sensation of sleeping "in" your mattress (vs sleeping "on" your mattress)
• The K-Class has a bit more memory feel, though both have "High" memory feel on our rating spectrum.
• The K-Class has a bit less bounce, though both have "Medium-High" bounce on our rating spectrum.

I hope that's helpful.