What are the main differences between the cheaper chairs and the more expensive models?

More expensive chairs will, like anything be more comfortable and made from better materials.

Daiwa Coarse & Match Fishing Chairs

What are the main differences between a ‘tandard camping-style chair and a fishing chair?

Most fishing chairs will be stronger and more stable on the lengths.

Are the chairs comfortable to sit in for long lengths of time?

This varies depending on the chair. Some will be more comfortable than others.

Can the chairs be adjusted for height and posture?

This varies depending on the specific chair.