I mean, we learned in Legion that Odyn created the Val'kyr after he had his glimpse into the Shadowlands (and traded his eye).
I do think that there is a difference however, even though this hasn't been said in any panel or anything, but it's from those lore-tablets in the Halls of Valor, that the spirit healers and Val'kyr are specifically undead, and not dead. Odyn wanted his val'kyr to be of both realms, which is why he had to make them undead, I think. If they were dead, they'd be Kyrians and not beholden to him anymore, but to the Shadowlands. When they broke free of him, they seem to have forged a connection to the Shadowlands, however, because now they serve as spirit healers still, funnelling souls either back to life, if they are still tethered to there for whatever cause or towards the Shadowlands (this last part was said about them specifically in the panels at Blizzcon).
Edit:
The problem here is that there is no source to be found for this. I've looked, because I've had this discussion and I was kind of sure I'd heard or read it somewhere, but... I could for the life of me not find it. Is there an actual source or are we just implying that, because it's a reasonable assumption in the context of WoW?