No he doesn't. He is talking about the Skyrim DLC plan. This is what he says:
"For Fallout 3 we did five DLCs," Howard told me during an interview last week at the DICE Summit. "That was a very aggressive path for us. Our plan now is to take more time, to have more meat on them [for Skyrim]. They'll feel closer to an expansion pack."
This isn't him defining the difference between the two. He sort of touches on them, but the most we can conclude from that is that the difference between DLC and an expansion pack is an ill-defined greater quantity of content, but by his own statement, Skyrim content is DLC and not an expansion pack.
The second link you post isn't a statement from anyone in the industry. As far as I can tell it's a random opinion piece on some no-name site. In any event, all that it says is that the difference is some unexplained amount of content:
In the aforementioned stories CDP pins the differentiation on the size of the content, but a lot of publishers just seem to always use “DLC,” even for very large pieces of content. Technically, expansions in the modern sense are just really big pieces of DLC. Dishonored’s two story-based add-ons, which Bethesda calls DLC, together comprise almost as much content as the base game. Grand Theft Auto IV: Episodes From Liberty City is a significant expansion. Maybe CDP just needs to inject the word “DLC” with the value that used to be associated with expansion packs, but one developer alone probably can’t do that. In any case, Witcher 3’s “expansion pass” supposedly contains around 30 hours of content for $25, and the October and early 2016 release dates suggests this is not cut content.
The reference to cut content is interesting because some old expansion packs were cut content (the best example being Tales of the Sword Coast).
The underlined comments suggest that the author actually doesn't think an expansion pack is different from DLC.
You are misinterpreting what Todd Howard is saying then. He is making a distinction because Dawnguard and Dragonborn, from his perspective, aren't just "DLC." He uses the DLC packs in Fallout 3 as a separation to show what he defines as traditional "DLC," and then Skyrim add-on content, which is different. He makes a parallel to Skyrim being closer to an expansion pack to suggest that Dawnguard and Dragonborn aren't as massive in scope as Shivering Isles, Tribunal, or Bloodmoon, but they are very much in the same spirit of that kind of experience. Dawnguard and Dragonborn are neither DLC or expansions, they are somewhere in-between.
You are missing some major arguments of the second post. The author clearly notes that there is a difference to what expansions were a decade or so ago to what DLC is today. Part of it is due to technology. Part of it is because the term "expansion" had a rather strict meaning while "DLC" was ambiguous. The issue today is that developers and alike have largely made the terms synonymous, when they never were, leading to this "arbitrariness" that you, and others, keep making an argument for.
The point is there was a difference between expansions and DLC in the past. Today, it's not so clear, thus there is a lot of confusion. What CDPR is arguing for is a return to the older days when expansions meant something, as CDPR argues "DLC" is a term that has largely lost meaning and been diluted, much like the phrase "MMORPG." To truly understand and grasp the depth of this situation, you have to appreciate and follow the history of these various terms, what they applied to depending on the particular platform, and how things have changed.