* politics: yes, they exist everywhere, but tend to be amplified at larger companies. polish your political skills, and one thing that I've learned is that it's important to "show, don't tell"
* fiefdoms: there are more of them, some more welcoming than others. be prepared for those that value power above all. you can't take it personally, or you'll go into a very dark place; "be the rubber duck", that is, stay floating no matter what and let the negative wash off of you like water off a duck
* duplication of effort: there likely will be tons of duplication of effort (even parallel projects doing the exact same thing), sometimes it's easy to work with others and come together for a common solution, sometimes it just plain won't happen (see fiefdoms). no real advices here, just that you need to be aware
* technology stacks: sometimes some groups will be stuck with what seem to be very old technology stacks, or things that don't seem to make any sense. look at the group you'd be joining and who they interact with, find out about the pain points before you join so you aren't surprised. even a small change can affect a lot of people at that scale, so approach changes and modernization gingerly.
Big companies can end up driven by incentives that are at best orthagonal to basic economics which means you often can't convince people to do things that make sense because they make sense.
If individuals are judged based on results against goals declared at the start of the period, they will tend not to do anything other than that. You can't say "the users want this", or "this will save $5 trillion dollars", or "we can't do our job without this" because those things don't matter to individuals. Instead, you have to argue for it to be put on a roadmap, or convince your management to convince their management to push them to do it sooner than 18 months from now. And you have to do it with a light touch, or there will be resentment.
let me provide an example of where more polished political skills might come in handy:
scenario 1, small startup - you're used to working very closely with a small team, know each others skills, strengths, and weaknesses, and can instantly drop in and say, "hey! it looks you're doing in a way that can be optimized, I'm doing the same thing, let's work together and do it right" without ruffling any feathers or destroying relationships.
scenario 2: big company, larger team, lots of cross-team work, same issue. "hi, I noticed that we're trying to work on the same thing and attempting to improve performance in similar manners. I'd hate to have us both duplicate this effort, do you have time to maybe bounce ideas off of each other so we can come to a better solution?" and knowing when to drop it when the answer is "no".
it's a difference in communication styles, which might be more difficult to adapt to when coming from a smaller organization.
does that help?
(note that I could also have said, "well, duh, just learn to communicate better!" but that would have been counter-productive in this case :) )
editing to add that I gave an example for one type of communication, sibling comments to this did a fantastic job of providing probably better examples.
In a startup you may be only needing to convince yourself, or, maybe, a co-founder. Comms are mostly 1-1.
In a larger company you'll need to persuade a set of people to greenlight your project, or convince your executive chain that your team is providing value, or convince other teams that they should support (or at least not actively hinder) your project or team.
Politics can be toxic, but with the most rose-colored glasses, it can just be the practice of working effectively in a larger community.
* politics: yes, they exist everywhere, but tend to be amplified at larger companies. polish your political skills, and one thing that I've learned is that it's important to "show, don't tell"
* fiefdoms: there are more of them, some more welcoming than others. be prepared for those that value power above all. you can't take it personally, or you'll go into a very dark place; "be the rubber duck", that is, stay floating no matter what and let the negative wash off of you like water off a duck
* duplication of effort: there likely will be tons of duplication of effort (even parallel projects doing the exact same thing), sometimes it's easy to work with others and come together for a common solution, sometimes it just plain won't happen (see fiefdoms). no real advices here, just that you need to be aware
* technology stacks: sometimes some groups will be stuck with what seem to be very old technology stacks, or things that don't seem to make any sense. look at the group you'd be joining and who they interact with, find out about the pain points before you join so you aren't surprised. even a small change can affect a lot of people at that scale, so approach changes and modernization gingerly.