I don’t understand the different tickets!
When you buy a train ticket, you enter into an agreement with the companies whose trains you can use. All tickets are subject to conditions that relate both to the class of travel and when and how the ticket may be used.
If the ticket is not used in line with these conditions, it will not be valid and you may have to purchase a new ticket at full price or you may receive a penalty fare. It is therefore important that you understand and comply with the conditions applying to the ticket that you are using. Speak to a member of station staff if you have any doubts of the validity of your ticket before you board the train.