Please what is the difference between a first class seat and a sight seeing seat or cabin? Thank you

The ticket price for sightseeing seat and first class cabin is much higher than the common first class seat. The differences are the location of the carriage, services provided and the comfort degree. The sightseeing seats are usually located in the carriage close to the train cockpit and there are only 3 seats in one row, which makes the space between rows very large.