Yes, first class rail carriages have fewer seats and are more spacious than coach. Buses are comfortable enough, but certainly more cramped than trains.
Thank you David
Train is often cheaper than bus if booked more than a week in advance. However the regional train from Tunes to Lagos can be very busy as was the case when I took a train on Tuesday. Most of the passengers were tourists, many were picked up at Tunes off the Lisbon train.
Also, most but not all buses are direct. Check carefully.