A dictionary, as it were. We'll start with Organized Rides.
Let's define an Organized Ride. These are events that have event directors with some amount of support staff enabling the event. They have (a) specific start time(s), (a) pre-planned, published route(s), (always) have some sort of entry fee (pay-to-play).
T-Shirt Ride (or Bicycle Rally): 90% of the "bicycle races" you see are actually T-Shirt rides. These are not races, despite what most of the participants might try to tell you. These are gatherings of recreational cyclists of varying levels of talent and skill, many with an over-inflated sense of capability, lightly spiced with a small number of local riders (read: racing experience) with some amount of "real talent." They're called t-shirt rides because you typically get a unique t-shirt with your paid $30-60 registration, although some give out other items like socks, hats, and other goodies.
Commonly as dangerous as races, sometimes not as well insured, heavily enabled by volunteers, with some known for the qualities of their rest stops (Best baked goods! Volunteers all in reed skirts and coconut halters!). Most rallies have some roving vehicle support (called SAG) and rest stops usually every 10-15 miles along routes typically ranging from 10 miles to 60 miles, occasionally with 100 mile routes.
Expect a race-pace start that quickly sheds the less talented/skilled while creating many opportunities for conflicts between people with fitness, talent, and those with less. Once the riders are suitably divided, groups tend to cooperate with the intent of keeping the pace high and finish as quickly as possible.
This set is the most likely to brag about how fast they did 100k. Mind you, they probably wheelsucked the whole way, and even if they survived the 99k they were probably dropped when the pace accelerates to sort out the "winner."
USAC Races: In the rare event you see a real bicycle race (in the US), it's very likely a USAC (USA Cycling) sanctioned race. These are events on partially closed courses where fields are made up of similarly-skilled riders enabling a real sense that anyone could win. This is where the "local talent" looks to be "discovered," even when the vast majority of them are a decade or more past any chance of being "seen," even if they were actually fast enough to catch someone's eye.
Races are where the real hard riding happens. If you think a T-Shirt ride is hard, you have experienced nothing until you're in a pack of evenly matched riders all riding near your limit as others strive to push everyone over their limit.
There is no doubt that these riders are among the most fit of all cyclists, but many take themselves or their hobbies too seriously and that arrogance makes them standoffish around most of the cycling community. (Especially commuters and the hipster set.)
To racers, finishing "on the podium" is really all that matters. And when they're on the podium, all that matters is being on top of the podium - i.e., first place.
For these riders, it's a point of pride to have a 30lbs bicycle with 20lbs gear, and riders that roll up on modern carbon with aero wheels are quickly ostracized. This set measures success by the mile, not by the minute; it's not about being fast, it's about how far you can go.
For this group, it's survival that matters. They won't talk about how fast they ride because, frankly, it's embarrassing. Instead, they'll try to one-up a racer's first place or a rally rider's 2h20m 100k with their survival of a 1200km permanent in the heat of summer.
UMCA Races: If you're at a timed event with some ridiculous distance to cover, able to have a team but can't ride together, and plain confused about what what the hell you're doing, you're probably at UMCA race. This is the intersection of the RUSA crowd and the USAC crowd, where speed and distance both matter, where you play the gamble between minimalist gear and the chance you'll need that gear to finish.
This is the world of no sleep. And (almost) everyone knows how to not sleep. This is about as accessible as racing gets, while being about as un-serious as racing gets; the range of participation shows that. When looking at the starting line, the only difference between a T-Shirt ride and a UMCA race is ... well ... nothing. There will just be fewer people at the UMCA race.
Many UMCA races have an "everybody's a winner" mentality, giving out trophies for being upright with a pulse - and having turned over the pedals for whatever minimum distance the event required. These events usually break down the competition by bicycle type (upright, recumbent, sometimes mountain), then solo riders by gender, age; or by team make-up, all men, all women, or mixed.
This makes for an interesting award ceremony, with sleep-deprived racers barely conscious as hundreds of over-sized trophies are awarded.
There you have it. A list of Organized Rides. Now you have a sense what you can expect when you decide to try one of these out.
Which you should! I've done all but Brevets (and, someday, when I'm slow, I'll do that too), and I've enjoyed every one of them.
Stay tuned for my next installment: Informal Group Rides.