>No ridiculously low level cap--no level cap at all, in fact
>The ability to keep playing after the end of the main quest, with bonus content depending on what factions you went with
>A much larger, more open world with more locations to find; the game really rewards unfettered exploration
>Boston is a huge, dense city rather than Vegas's three buildings
>The Settlement/building/settlement defense system
>A perks system that actually encourages different character builds
>Better item crafting
>Much cooler power armor (with jetpacks!)
>No invisible walls
>An excellent "survival" mode; I can't imagine playing without it
>Flying around in vertibirds
>Along with the jetpacks and vertibirds, just a more "vertical" game in general; there's a lot to find on building tops and elevated highways
>Behemoths and mirelurk queens
>A gun that shoots actual cannonballs
>The ability to call artillery salvos on enemy fortifications
>Can blow off enemies' individual body parts, allowing for more interesting combat tactics overall