History Bits:
Chaosium wanted to be primarily games designers rather than games publishers (they designed West End Games "Ghostbusters" which was the original d6 system that spawned thge WEG Star Wars line). Avalon Hill was a successful (Board) Games publisher who wanted to break into the RPG market. They had previously picked up a couple of Chaosium board games (White Bear & Red Moon, published by AH as Dragon Pass, which is the first Gloranthan game, and the ELRIC board game), so on the face of it the deal to allow AH to publish RQ looked like a good one...
When the deal went sour, and when AH was bought up by Hasboro, but still retained the RQ name, Chaosium could not put out anything for RQ. Greg was working on "a new Gloranthan RPG" - which was, at one stage more similar to Pendragon - this was to be "HeroQuest" - a sort of "advanced" RQ that had been promised many years ago, before the AH deal was even thought of!
To add to the general confusion, in the intervening period Games Workshop, together with Milton Bradley produced a fantasy board game called "HeroQuest" and "Advanced HeroQuest" - this has nothing to do with either RuneQuest or Glorantha.
Following the break up of Chaosium, Greg set up Issaries to publish his new game, written by Robin Laws. As HeroQuest was unavailable this game was published as Hero Wars.
Subsequently Greg was able to acquire the trademarks to both HeroQuest and RuneQuest which had lapsed under US Law. A greatly revised and much improved version of HeroWars was produced as HeroQuest, and the RQ trademark, and the rights to produce Gloranthan 2nd Age material were licenced to Mongoose.
The only similarity between HeroQuest and RuneQuest is that they both use Glorantha as a (potential) Campaign world.
There are rather more similarities between Hero Wars and (Mongoose) RQ however. Not in terms of the rules, nor the settings (although again, both use Glorantha) - more in terms of both being rushed to market without sufficent proof-reading allowing fairly basic errors through. Also both eschewed the "standard" RPG rulebook format in favour of one intended to be more acceptable to "Standard" book stores - not that either game has/had a noticable presence in standard bookstores....