Eurotunnel and Eurostar are the two operators through the Channel Tunnel between Folkestone and Calais.
Eurostar is the fast passenger train service from London St Pancras International, Ebbsfleet (M25) and Ashford (Kent) to Calais, Lille, Paris, Brussels, Avignon etc
Eurotunnel is the vehicle train alternative to the ferry between Folkestone and Calais (Coquelles) which has a journey time of 35 minutes. It is certainly fast and the terminals at both ends are impressive. And of course, there is no disruption or discomfort in the event of bad weather at sea. However, it does tend to be more expensive than the short-sea ferry routes and if you are coming from some distance it can be that the slower and more leisurely ferry crossing is more relaxing - and of course you get to see the French coast and the White Cliffs of Dover, and can have a meal or snack on the boat.
|Eurostar (passengers)||Eurotunnel (cars and other vehicles)|