Casual vs Competitive Play
On social media pages and in forums, you will hear people throwing around the terms "competitive," "casual," "fluff," and "cheese," with reference to different kinds of game and different kinds of army lists. (Veteran players also talk knowingly about a mysterious phenomenon called "the meta," which sounds like the angry ghost of a deranged Aunt, but isn't.) Here is what these terms mean and why it matters:
Competitive Lists
Competitive lists are lists designed to win the game as quickly as possible against any opponent; a player designing a competitive list is essentially trying to win the game before it starts. Every single unit is a competitive list has been selected to perform a very specific job: eliminating heavy infantry, seizing objectives first, etc; as such, these lists tend to be composed of the most effective units available to a particular faction, optimized with the most merciless sub-faction bonuses and stratagems available. Competitive lists are typical in tournament play.
Casual Lists
Casual lists may feature a greater diversity of units than competitive lists and are likely to include at least a few units that have been selected simply because they look cool or are thematically appropriate to a particular sub-faction. For example, an eldar player who runs craftworld Iyanden may want to include at least 10 wraithguard and a wraithknight in all her lists, while a Biel-Tan player may want at least 50% of her units to be aspect warriors, etc. Casual lists may still designed with winning in mind, but winning is not the only or even the primary consideration before the game begins.
For more about my own experience learning to navigate the differences between competitive and casual play, click here.
Fluff Lists
A "fluff" list is a casual list composed around a cool concept or a goofy gimmick; it likely features rarely used units that are may seriously reduce an army's chance at winning, but will be fun to play. For an eldar player, this might mean trying to run and all-wraith list, or a list composed primarily composed of Corsairs and Prince Yriel.
Cheese Lists
A "cheese" list is a competitive list taken to the extreme. Cheese lists make maximum use of one or two specific advantages or special rules, usually by spamming particular units to create synergies that are likely to be annoying even to other competitive players. One 8th edition cheese list involved running 9 vibro cannons with the "expert crafters" craftworld trait, but 9th edition rules have blocked the synergies that made that one so effective. In general, 9th edition rules have done a pretty good job of cutting down on cheese.
The Meta
The "Meta" refers to the way people are currently building and playing armies and therefore what sorts of obstacles your army lists are most likely to encounter. The term is short for "meta game," that is- all the stuff you need to think about aside from the actual rules if you want to win. To put it another way, thinking about the meta is just thinking about what enemy armies and units you are most likely to face and planning accordingly. Your local meta is whatever lists and play styles you are common in your local store or play group, while "THE Meta" refers to the wider world of competitive play at major tournaments.
Why this Matters: How Not to Be a Jerk
9th edition 40k is a super fun game as long as you and your opponent both show up willing and able to play the same type of 40k. Both casual and competitive 40k are a blast. What is not a blast- what really sucks in fact- is showing up to what you think is a casual game to see an army on the other side of the table that you know will destroy you on turn 1 regardless of how you play. It also sucks to ruin someone else's evening doing the reverse.
The solution: communicate. Ask your opponent's in advance if they want to run tournament lists, casual lists, or fluff lists, and then either accommodate them or ask them to accommodate you. Also, if you are playing against someone whom you know has a much smaller collection than you do and just doesn't have the resources to make a highly competitive list, consider building a list that is comparable to what you know that person can field.
What not to do: Don't adopt the attitude that anyone who doesn't play the way you like to play is doing it wrong. When I got back into 40 a few years ago, I took a few bad beatings from some competitive players and came to the conclusion that they were playing the game the wrong way, that 40k was intended for casual play and these opponents were min-maxing troglodytes. In retrospect, that was utterly stupid on my part. (If you want to read more about my delightfully awkward return to the hobby after many years, click here.)
It's really fun to strategize about the most effective ways to overcome various types of army with the resources we have available as Craftworlds players, and then to watch those plans try and survive first contact with a thoughtful opponent. It's also really fun to throw some models together around a theme, add your prettiest HQ or titanic unit, and push some space elves across the table while eating pretzels and bantering about the crazy story that's unfolding.
If you learn to play both versions of the game, you will probably get a lot more out of the hobby.
