Tesla armor is a name given to various kinds of armor designed to protect against directed energy attacks. They were constructed from plans left behind by Nikola Tesla that were confiscated by the US government after his death.
This armor is designed to deflect energy weapons. However, its protection against impact attacks falls far short of what its military designers were looking for. Its three Tesla Attraction Coil Rods disperse a large percent of directed attacks. However, since its protection against conventional firearms is comparable to the post-war metal armor, its popularity was limited, although some surplus suits made their way to National Guard armories and from there to the wastes.
This armor is a variant of the Enclave's post-War advanced power armor Mk II jury-rigged with a Tesla device that is capable of dispersing a large percentage of the damage done by directed-energy attacks. It is unrelated to the original Tesla armor. (This suit of power armor can be obtained in Fallout: New Vegas with console commands)
This version was possibly a prototype during this period before the complete destruction of Navarro by the NCR. Similar to the Enclave Tesla armor from Fallout 3, the Remnants Tesla armor has multiple energy capacitors on the shoulders, presumably channeling power towards weapons that utilize that energy. The Gannon family Tesla armor is the only set that remains in 2281.
This version was likely designed after the Great War by the Midwestern Brotherhood of Steel, based on the pre-War model. The main difference is that its Tesla Attraction Coils are not in the form of protruding rods, like in the earlier variant.
The Vault-Tec Tesla armor developed in the Secret Vault is different from other pre-War or post-War variants. It appears to be a bit similar to Tesla power armor. They are the two tesla coils on the shoulders for dispersing a large percentage of directed energy attacks.