Elk and caribou are basically the same, right?

Caribou are reindeer. "Elk" is the North American word for a large species of deer—not the same as reindeer/caribou. "Elk" is used in European English for the animal that in North America is called moose.

They look almost the same, R1.

Caribou are smaller than Elk. Also, female caribou have antlers; female elk and moose do not.

Elk are basically deer with grey coats.

Caribou are great eats. When I lived in Quebec I used to go hunting/camping in the winter in northern Quebec where they're plentiful. They make a great stew. Moose is gross. It's like chewing gum.

Are they all good eggs?

That's awful, R5.

What's terrible? Hunting and eating a caribou? They are delicious.

There are some certain correlations between European terms and American terms.

Caribou (American) = Reindeer (European)

Elk (American) = Red Deer or Wapiti (European)

Moose (American) = Elk (European)

Caribou migrate...reindeer don't.

Sure OP...they all look the same to you.

Moose is delicious if ground

From Wikipedia:

The females usually measure 162–205 cm (64–81 in) in length and weigh 80–120 kg (180–260 lb).[73] The males (or "bulls" as they are often called) are typically larger (to an extent which varies between the different subspecies), measuring 180–214 cm (71–84 in) in length and usually weighing 159–182 kg (351–401 lb).[73] Exceptionally large males have weighed as much as 318 kg (701 lb).[73] Weight varies drastically between seasons, with males losing as much as 40% of their pre-rut weight.[74]

Shoulder height Is usually 85 to 150 cm (33 to 59 in), and the tail is 14 to 20 cm (5.5 to 7.9 in) long.

The reindeer from Svalbard are the smallest. They are also relatively short-legged and may have a shoulder height of as little as 80 cm (31 in),[75] thereby following Allen's rule.

Elk is much bigger than a deer (see pic below)

Elk are more than twice as heavy as mule deer and have a more reddish hue to their hair coloring, as well as large, buff-colored rump patches and smaller tails. Moose are larger and darker than elk; bulls have distinctively different antlers. Elk gather in herds, while moose are solitary. Elk cows average 225 to 241 kg (496 to 531 lb), stand 1.3 m (4.3 ft) at the shoulder, and are 2.1 m (6.9 ft) from nose to tail. Bulls are some 40% larger than cows at maturity, weighing an average of 320 to 331 kg (705 to 730 lb), standing 1.5 m (4.9 ft) at the shoulder and averaging 2.45 m (8.0 ft) in length.[23][24] The largest of the subspecies is the Roosevelt elk (C. c. roosevelti), found west of the Cascade Range in the U.S. states of California, Oregon and Washington, and in the Canadian province of British Columbia. Roosevelt elk have been reintroduced into Alaska, where the largest males are estimated to weigh up to 600 kg (1,300 lb).[25] More typically, male Roosevelt elk weigh around 300 to 544 kg (661 to 1,199 lb), while females weigh 260 to 285 kg (573 to 628 lb).[26][27] The smallest-bodied subspecies is the tule elk (C. c. nannodes), which weighs from 170 to 250 kg (370 to 550 lb) in both sexes.[26]

So R5, it is on you to introduce OP to 'Jean-Guy The Caribou Christmas Stag'

Jean-Guy everyone.. ..

Size comparison below

“The moose is the largest member of the deer family, and stands taller at the shoulder than the largest saddle horse. ”

Wikipedia:

On average, an adult moose stands 1.4–2.1 m (4.6–6.9 ft) high at the shoulder, which is more than a foot higher than the next largest deer on average, the elk.[92] Males (or "bulls") normally weigh from 380 to 700 kg (838 to 1,543 lb) and females (or "cows") typically weigh 200 to 490 kg (441 to 1,080 lb), depending on racial or clinal as well as individual age or nutritional variations.[93][94] The head-and-body length is 2.4–3.1 m (7.9–10.2 ft), with the vestigial tail adding only a further 5–12 cm (2.0–4.7 in).[95] The largest of all the races is the Alaskan subspecies (A. a. gigas), which can stand over 2.1 m (6.9 ft) at the shoulder, has a span across the antlers of 1.8 m (5.9 ft) and averages 634.5 kg (1,399 lb) in males and 478 kg (1,054 lb) in females.[96] Typically, however, the antlers of a mature bull are between 1.2 m (3.9 ft) and 1.5 m (4.9 ft). The largest confirmed size for this species was a bull shot at the Yukon River in September 1897 that weighed 820 kg (1,808 lb) and measured 2.33 m (7.6 ft) high at the shoulder.[97] There have been reported cases of even larger moose, including a bull that reportedly scaled 1,180 kg (2,601 lb), but none are authenticated and some may not be considered reliable.[97] Behind only the two species of bison, the moose is the second largest land animal in both North America and Europe.

I still don't think I could tell the difference between them if I came across one in the wild.

This says that although reindeer and caribou are the same species they are different.

R17, they are easy to tell apart if you have seen pictures of all three.

Caribou can be quite tame if you're patient with them, you can even saddle one up and ride one if you're under 100 pounds or so. I would never try that with an elk, they are mean, spiteful, and will bite and buck you off...

Once you eat some caribou all meat will pale in comparison.

Pale like veal?

R1 'European English' ? Never heard of it.