Bama Lethwei has been discussed here before - If you search for it you should be able to find out a good bit. Basically, if you go back far enough to Siam, you see that much of Lethwei and Muay Thai were developed around the same time by the same people. There are local differences much the same as certain boxing gyms tend to train certain things others might teach a little differently. Head butts are allowed, and traditional fights lasted until one fighter was not physically capable of continuing. These days it looks a WHOLE lot like Muay Thai.
The shovel kick is around today and it basically fires hard and fast from the ground at around a 45 degree angle to the opponents thigh / knee (either inside or out) rather than the traditional Mauy Thai roundhouse that tends to actually hit at a downward angle. Many people train this kick but call it something different.