For trading and whatnot, we don't use regular cars or trucks. The vehicles put to use in such scenarios are more different and have different licensing needs too. They are placed in two categories, called HGV and LGV. Earlier, the LGV was used for both of them. However, over time, the confusion was dropped by separating them both.

For the proper HGV training, you would need to understand the points where they both differ and where they share similarities. Especially before you go get a license, you need to be somewhat familiar with the topic.

LGV vehicles
As mentioned earlier, LGV was meant for two terms, the first of which is light good vehicles. What this means, is that all those vehicles that do not weigh a bit above 3.5 tonnes can fall under this category. If a vehicle is labeled HGV, it is safe to assume that it weighs below 3.5 tonnes.

The other term that LGV stands for is "large good vehicles". Thus, every vehicle which holds a weight of more than 3.5 tonnes will be considered a large-good vehicle. The vehicles included are vehicles like box vans, tippers, curtain side lorries, lorry's buttons, drop sides, Moffett, ADR, refrigerated trucks, HiAb, etc.

Every vehicle that weighs more than this has its license category so you would have to look out for that.

HGV vehicles
When vehicles were to be labeled, there was confusion amongst them regarding which is the light good vehicle and which is the large-good vehicle when you are labeling both of them as LGV. So from there, the term HGV came around. HGV stands for heavy good vehicles.

There isn't much difference when it comes to the licensing regarding nothingness categories. The place where you have to differentiate is how much tax every vehicle is supposed to pay.

Since every vehicle carries itself differently on the road, they pay unique taxes. A vehicle that is, let's say, 5 tonnes, will cause more damage to a road than a regular car. So when the idea of road taxation was introduced, the vehicles were categorized and their taxes were put into place.

Therefore, the licenses are the same, it is just the taxation that differs.

Types of HGV licenses
There is little to no difference in the kinds of licenses offered for different vehicles. When the weight exceeds 3.5 tonnes, there are only so many categories that the vehicles can be divided into. However, if you hold the license for a certain type of vehicle, you will not be able to drive the vehicles that fall outside that category.
So, if you are planning to be a driver, you would have to choose what kind of vehicle you are planning to drive early in your career.
Here are the types of licenses you can go for:

C1
The C1 license is just one step ahead of the regular driver's license. It is the first and foremost license that you can get your hands on. If you manage to secure this license, you will be allowed to drive vehicles that are above 3,500 kilograms. However, you should be careful that the weight of your vehicle should not exceed 7.5 tonnes.

There are little to no limits around the shape or nature of the vehicle that you are allowed to drive in this category. You can tow the trailer, have a truck, or drive a lorry in this category.

One point worth noticing is that if you got your license before 1997, your license accounts for a regular license as well as the C1. So make sure you note that.

C1+E-
This license will allow you to drive a vehicle that is more than 7.5 tonnes. Plus, if you plan to tow a vehicle with yours, that should be up to 750 kgs. The weight of your vehicle and the towed vehicle combined cannot be more than 12, 000 kg though. There is only a little math that you would need to do. So, keep the weight of the main vehicle above 7.5 tonnes, the weight of the towed one below 750 kgs, and the total below 12000 kgs too.

C-
This category allows you to drive vehicles between 3.5 and 32 tonnes.

C+E-
If you are planning to drive more than one type of vehicle then this is the vehicle you should go for. This license will allow you to drive any kind of vehicle that is mentioned in the categories above. The E in this category stands for entitled.