So - What are the classifications for the types of roads / tracks?

Footpath
If the path is used for walking only, it is a footpath. This is different from the pavement alongside a road, in that it means the whole width of the highway. Footpaths are usually just tracks, and are rarely surfaced or lit.

Bridleway
Bridleways are also footpaths, but additionally users are permitted to ride or lead a horse, and ride bicycles. Horse drawn vehicles are not allowed. This may not include other animals, although a donkey or mule is classed as a horse for these purposes. Cyclists must give way to pedestrians and horseriders. Motorcycling is not allowed. Bridleways are not necessarily surfaced, and because of this a well used bridleway can sometimes be effectively impassable for pedestrians.

Byway open to all traffic (BOAT)
BOATs allow the use of wheeled vehicles of all kinds, but the highway is normally used for walking or horse riding. Off-road driving for recreational purposes often happens along such highways. Again they are not surfaced, and can get very wet and muddy for obvious reasons.

Road used as a public path (RUPP)
Some highways are still legally classified as a RUPP, which is a very vague definition. Most of these are being reclassified as BOATs or other highways, but this process will go on for many years yet. Meanwhile their status remains ambiguous, and probably local custom is the best indication of what you can and cannot do.

Restricted Byway
A category of right of way created under the Countryside and Rights of Way Act 2000. A restricted byway allows a right of way on foot, on horseback, or leading a horse, cycling and for any vehicles other than mechanically propelled vehicles.

Green Lane
This definition has no legal status. It usually refers to a BOAT or RUPP, but in some cases a road called a green lane may have no right of way along it at all.

Permissive Path
It is possible for landowners to allow access over their land without dedicating a right of way. These accesses are called permissive paths. To the user they are often indistinguishable from normal highways, but there are some important differences.

A permissive path must have some sign or similar indication that it is not intended to be a right of way
The landowner can close off or divert the path if they wish to do so, without any legal process being involved
The landowner can make restrictions which would not normally apply to highways, for example to allow horse riding but not cycling, or the other way around.
Permissive paths are commonly found on land owned by a body which allows public access, such as a local authority, a Railway Authority, or the National Trust.

Pavement
Pavements are simply part of the highway which they go alongside, and do not have any separate existence. So normally they are not considered as paths in their own right, although there are often other pathways in built up areas which may be public rights of way, and sometimes other rights of way (e.g. a footpath) can go along a pavement - this is often where a new road has been built across or along an existing, older, right of way. Common law ensures the right to pass along any highway, and in the case of pavements (paths alongside vehicular roads, usually in urban or suburban areas) the pavement is usually included in the highway. This means that it is an offence to obstruct a pavement. However, it does not mean that users can cycle or drive on the pavement, unless there are special measures to allow this (e.g. a designated cycle route).