Plantar fasciitis is by far the most used to explain heel pain.
Some use other terms like "plantar fasciitis" or “heel spur”. The term "plantar fasciitis" means medically that the fascia under your foot is inflamed! The belief wants this inflammation to be the cause of the pain.
However, for a few years already, scientific studies show that by analyzing injured cells under a microscope, the tissues are rather in phase degenerative. So there would be little or no inflammation, but it would be a change in fibers. This results in a general decrease in sound elasticity causing tension when walking. In other words, the plantar fascia "Weakens".
The most general and exact term to remember for this condition is plantar fasciopathy.
Plantar fasciitis is often confused with Lenoir's spine, a synonym for heel bone, which is actually just a bony growth formed at the site of insertion of the fascia into the heel bone.
This thorn is not the problem in itself; rather, it is a variant observed on the associated radiograph, without being the cause. So Lenoir's spur and plantar fasciitis are often misused medical terms to describe heel pain.
It's important to understand that Lenoir's thorn is not the cause of the pain, it is not a sharp bone that hurts when you step on the ground. For example, you may have very severe plantar fasciopathy painful without having a Lenoir thorn and, on the contrary, having no heel pain and having a Lenoir thorn on your x-rays.
In practice, it is more important to know the thickness of the fascia, to follow the evolution of the pathology, whether there is a Lenoir thorn or not.