primal n Eikon

Sorry if its been asked already but are primals n eikons the same thing?

No. And yes. But no. And yes. (Kind of.)

The Garleans have been using the term Eikon (pronounced icon, as in false god) to describe what we in our time call Primals because the Allagans used the term, and Garlemald is all about trying to emulate Allag. However, the entities that we call Primals manifest under different conditions than the 5,000 year old beings that Allag called Eikons, however similar they may be. Primals (of today) exist via Aether & Prayer, whereas Eikons don't seem to draw their power from zeal, so how they manifested and by whose hand is completely unknown.

Primals and Eikons may end up having much in common in the end, or they may not - we just don't know. All we know is that the Elder Primal Odin is technically also an Eikon, which is our biggest hint about their true nature so far. Honestly, I'm not 100% convinced that the two are more different than alike. The Eikons seem to be slightly less "primordial beings" of the Land and its elements, and more humanoid gods of war, for lack of a better term.

I think we'll learn that Eikons were once plentiful, with the Warring Triad being the most powerful from among their number. I think we'll also find that Allag tried to harness their power but it backfired on them in a big way, thus leading them to develop the technology to entrap them.

It depends on who's using the word "eikon."

Eikon originates as an Allagan term for a being we don't fully understand yet (the Warring Triad, Odin).
Primal refers to another entity which we have a better, but still incomplete understanding of (things like Shiva, Bahamut, Ifrit, etc).

However, Garleans appropriated the Allagan term "eikon" and use it to refer to "primals" in the current era which can lead to some confusion.

EDIT: Moose might say it better, BUT I'M LEAVING IT HERE.

I honestly won't be surprised if Eikons turn out to be FFVI's espers; essentially true living, breathing aetheric beings as opposed to mental constructs of them.

We really don't know anything beyond what Moose has already said though. Eikons are more powerful and don't rely on prayer for that power. Allag imprisoned many of them all over the planet and we're likely to be unearthing some of them in future.

The biggest question I have at this point though is where Eikons get their aether from. Primals draw it from the land and it is this leeching of Hydaelyn's aether that makes them such a major threat that cannot be ignored even if they are not being aggressive. The Warring Triad has been supplying aether to Azys Lla for millenia though. Have they been leeching Hydaelyn for thousands of years for that aether? Or do they get it from somewhere else, or even generate it themselves?