As an attempt to expand our Fallout Series articles, i will be listing and comparing some unique features of Fallout 3 and New Vegas that makes each game unique on its own way. Since both these games are built on top of same engine, i won't be covering Fallout 4 and Fallout 76, as they look's like completely different games when put side-by-side along with the previous games of this series specially in graphics, character building mechanics and base building systems.
By comparing Fallout 3 to New Vegas our main goal stays far from writing a review about weapons and mechanics comparison since New Vegas is way better than Fallout 3 by rough miles in these aspects. What i will be covering through is mostly game lore, freedom of exploration and some in-game details that may go unnoticed on my previous articles.
Before our article proceeds i'd like to state i am a huge Fallout fan, but even if my Fallout experience and my writing skills are not enough effort to create and provide a robust and fun-to-read article that correctly showcase the main aspects of these awesome games as they deserve or if i miss any core or essential topic in this monologue, i ask politely to any kind reader to comment bellow so i can fix any incorrect or misleading information that i may have share while writing this this article.
Also, i'd like to state that even though i wish i could expand this article as must as i want, i will be unable to be up to the task of fulfilling every major aspect of both these huge and incredible games since they provide a first-hands experience of being top-sellers RPG and contain a lot of trivia and details, a lot more than i can cover in a single article.

First and foremost i'd like to say that Fallout 3 gives you a freedom of explore and random encounters by far more interesting than New Vegas, and when i say by far, i really mean it. Fallout 3 has no environmental strong monsters barriers in any direction at the very beginning, so you basically leave the vault and can go anywhere you want from there.
Despite the fact that Fallout 3 has a slow 'leaving the vault phase' at the beginning, one which is very long and boring when compared to character building on New Vegas, i have to say the Fallout 3 is more fun at early game. Maybe this can be compensated by the fact that on New Vegas, at late stages, you can choose between multiple endings and has a higher opportunity to pick end-game choices, and that is a plus for New Vegas.
By extent, Fallout 3 random encounters are by all means the best among the two games. Many times while exploring this game you will face yourself in the middle of unexpected brawls among non-playable dudes and creatures. Sometimes it even gets epic, like facing two Yao-Guai battling a single Deathclaw in the middle of a talon company mercenaries vs raiders gun fight while a merchant caravan passes by. I would not be surprised if in same battle a super-mutant squad full featured with a behemoth armed with a hand hydrant pop up and begging spinning mini-gun bullets everywhere too. This incredible and each play through uniqueness is due to the fact that monsters in Fallout 3 not only randomly get spawned sometimes, but alto have three types of zones they walk around in: the attack zone, the walk zone and the 'back to spawn location' zone. When one or more creatures get close enough they interpolate the attack zone of each other, triggering a battle that otherwise would be unexpected. That gives the game it own life and feeling, one that is hard to come by on New Vegas but one that we can see in other Bethesda games like The Elder Scrolls: Skyrim.
On the other side, New Vegas offers a greater challenge to those willing to adventure either on lower or higher levels. Opponents in this game sometimes have high damage thresholds that can only be effectively bypassed by using special armor piercing ammunition, the overall game also feels to offer more challenges from beginning to the end.
We could also consider that both of these games have great in-game radios, with music worth listening. I personally prefer the Fallout 3 Galaxy News Radio, but that's a personal choice and i will leave to you guys to decide what flavor suits better your music style.
When talking about community mods from both games, both of these games offers great mods and it's hard to decide which mod ecosystem is better, although it's probably New Vegas, since the game is more recent and has a bigger mod-base maintaining community. Bellow i will list some mods from both games that i personally like, so you guys can give'em a try and check if any of those matches your personal liking's.
Another thing to consider is the DLC's. While both games have great dlc's, i would highly recommend New Vegas DLC's over Fallout 3 ones. In my personal and humble opinion, the DLC's i like most are Honest Hearths and Sierra Madre. When you think about Honest Hearths, it's impossible to don't feel attached to Joshua Graham, while when playing Sierra Madre, despite of the linearity of the DLC, it provides an great ending with awesome loot and a completely feel of strangeness and desolation that you don't feel too often in the main game and is a big add up to the overall plot. Somehow, disregarding the fact that every moment you are inside Sierra Madre you just want to dig your way out of it, when you complete the DLC and manage to escape, a complete feeling of 'they could've made this DLC takes a bit or two longer to complete' hits in. Some people hate these expansions, and yet some say's Point Lookout from Fallout 3 is the best choice, some still love it love, as per myself, i go full body and hands on with the last group.
This next section will be short as it can be a very extensive topic and at some point maybe even will to receive an entire article dedicated to only to this. Fallout factions are of huge presence among both games, but be shocked: unlike most people think, New Vegas has only two factions more than Fallout 3. This is a fact that may surprise even some hardcore Fallout players as i surprised myself when i found it, since people tends to hype a lot about New Vegas factions and how picking one faction or another can affect the player's end-game.
Quickly skipping the previous section a more interesting fact emerges when we talk about Fallout 3 and New Vegas YouTube content creator communities. To be extremely sincere, i am not entirely sure about which community is bigger, have more content creators and have higher audience, but i'd totally bet all my Atomic Wrangler chips in New Vegas. There is A LOT of video content in YouTube for both these games, but i am pretty sure that New Vegas contains more videos and audience by a far rough miles from the Capital Wasteland to The Mojave. Would be cool to have some statistics about it, but i am not even sure on how to find this. If we follow the same logic, New Vegas surely have the biggest fan-base of 'em, and i personally like both games, but somehow the freedom to explore Fallout 3 from the very beginning ends this article for me with a big tell-yall-to-do: If you want to start playing Fallout, start on Fallout 3 and play New Vegas once you explored the full Wastes of the first game. Time will payoff as enjoyment.

Now i want to call a small call-to-action: Which of those do you prefer?