There are 4 different LGV/HGV licence categories – C, C+E, C1, and C1+E.
Category C (also known as Class 2) means you are licenced to drive vehicles that are above 3599 kg in weight or a trailer of 750kg in weight.
Category C+E is a Class 1 licence that covers everything in Category C but also includes trailers that weigh more than 750kg.
With a Category C1 licence, you can only drive vehicles that weigh between 3500kg and 7500. For trailers, you cannot drive anything heavier than 750kg.
Finally, the Category C1+E licence gives you C1 licence privileges with the added benefit of driving a C1 vehicle with a trailer that weighs more than 750 kg.