Hello!

I like reading about mythology and one thing that kind of stumped me was Ares' sons. Whenever he went into battle he rode in a chariot along side his two sons: Phobos (fear) and Deimos (terror).

I always thought the two were synonymous with each other, but if they are identified as separate entities there must be some kind of distinction. What is the difference between the two?

Thank you in advance for replying.

Well, Phobos contains the first episode "Knee Deep in the Dead" and Deimos contains the second episode "Shores of Hell" so...

Oh.

Ooooooh...

Phobos is also the name of the DLang standard library. That's why I recognize it and came here half wondering if it was a programming discussion.

Phobos rises in the west and sets in the east, while Deimos rises in the east and sets in the west.

Since they're twins, I guess it's just slightly different aspects of the general fear that war brings. Apparently they never actually appeared as characters in any Greek stories.

Phobos, which gives us phobia in current usage is understood to be more about panic and fear / terror as hysteria.
Deimos is more existential terror, dread, woe, that sense of constant powerlessness.

As aspects of Mars, you can imagine the first as the sudden panic that makes you run away from battle impulsively, whereas the second more like that overall feeling that you're going to die because you're a soldier.

That said, all these things are pretty much guesses based on very little data. Perhaps native greeks have access to better sources.

Deimos is the incarnation of war's freakishness (of the macabre, in one aspect and sense). Phobos is the incarnation of war's horrors (of the fear, in one aspect and sense). They were both begat between Ares and Aphrodite. They escorted Ares/Mars in the battlefields as chariot escorts.

Goddess of Slaughter, "Enyo" also followed them, together with the goddess of conflict "Eris", the "Cyres" (mythological creatures) who sucked the blood of the dead and Cydemos, the incarnation of battle's ruckus (all this clang of metal and noises).

Today, Phobos and Deimos are names from two of planet Mars' natural satellites in orbit around him. How come the sudden interest in those two, though...?

The interest isn't sudden, I've had that curiosity for a while now. The reason I asked is because I was confused. In the English language fear and terror are pretty much interchangeable. I think something might've been lost in translation.

They are often used interchangeably. They do have somewhat different shades of meaning. Compare the different senses of each: fear | terror

One way I would characterize the difference is this: If you have a phobia of snakes, then walking in a wilderness area where snakes are known to be found might cause you to feel fear (dread of possibly encountering snakes); if you then happened to actually trip and fall, and hear the rattle of a rattlesnake only a couple feet away, you would feel terror (extreme dread, based on the immediate threat of being confronted with your fear). (And if some guy were to walk up to you just then and, with no warning, dump a box of snakes onto you, I suppose you might feel horror. =) )
That's my interpretation, at least. :)