Which is better for taking notes?

The Scribe. It ships with the Premium Pen and supports writing on the page, margin notes and PDF annotation. The Colorsoft has no pen support at all.

Which is better for reading comics?

The Colorsoft, because it shows color. Its 150 ppi resolution is lower than the Scribe's 300 ppi, so fine text and line art look softer.

Can I read the Colorsoft in the bath?

Yes. It is rated waterproof, which the Scribe is not. The Scribe should be kept away from water.

Which lasts longer on a charge?

The Scribe, rated up to 12 weeks of reading at 30 minutes a day with wireless off. The Colorsoft is rated up to 8 weeks.

Is the Scribe worth stepping up to over the Colorsoft?

Only if you write or read large PDFs. For plain book reading the Colorsoft is lighter, waterproof and shows color, which the Scribe cannot.

Which is easier to hold for long sessions?

The Colorsoft at 215 g. The Scribe weighs 433 g, roughly double, so it is better rested on a desk or propped up.

Amazon Kindle Scribe vs Amazon Kindle Colorsoft

Buy the Scribe if you write, annotate PDFs or read large pages; buy the Colorsoft if you mainly read books and want color covers, comics and waterproofing. The Scribe is a 10.2-inch 300 ppi monochrome tablet with an included Premium Pen, so it is the only one of the two built for handwriting. The Colorsoft is a 7-inch color reader at 150 ppi, far lighter at 215 g against 433 g, and rated waterproof. Owners rate the Colorsoft higher, but the Scribe's ratings come from a much larger pool of buyers.

Choose the Kindle Scribe if you take notes, mark up PDFs or want a big 10.2-inch page for reading.
Choose the Kindle Colorsoft if you read in color, read in the bath or pool, and want a light one-hand reader.

Prices

Amazon Kindle Scribe: $289.99 at eBay (last seen Nov 13)
Amazon Kindle Colorsoft: $289.99 at Uber Eats (last seen Nov 13)
Difference: both cost the same at the latest prices (Nov 13)