Fallout has never had as much content, quest wise at least, as elder scrolls, mostly because the factions in fallout tend to be tied to the main quest and thus there generally are no major questlines you can do besides that.
For example, Skyrim had Thieves guild, Dark Brotherhood, Mages College, and Companions, plus the civil war. guilds had nothing to do with main quest, but had quite a bit of content and longish dungeons and Civil war was only partially related to main quest. Compare to basically every fallout game, which has what for major questlines? um....I Guess you could do each faction up until the stopping point where they all interweave into the main quest....but that is it. No other major questline.
this holds true to every fallout/elder scrolls game as well.
space wise, and dialogue wise, it is FAR bigger then skyrim,