It’s hard to tell some animal species apart. Is that a jaguar glaring balefully at you from the shadows, or a leopard? A lizard slithering on the ground, or a salamander? Fear not—we’ve got you covered. Here are some (almost) fool-proof methods for distinguishing between seven pairs of commonly confused creatures.

1. Moths vs. Butterflies

This one might seem like a no-brainer. Most people think of butterflies as colorful garden visitors, whereas those drab moths only emerge at night to bonk against your porch light. But not so fast.

Moths and butterflies belong to the scientific order Lepidoptera—and it’s a huge, spectacularly diverse group, with tons of species that defy your expectations. Some moths fly during the day, hovering at flowers and drinking nectar. Moths can be spectacularly colorful, like this Madagascan sunset moth. And there are plenty of dull-colored butterflies, such as the brown-gray common ringlet and the grayish Avalon hairstreak.

So how can you tell them apart? One of the best methods is to look at the antennae (those long appendages that stick out from the head). With some exceptions, butterflies have a thickened part at the end of the antennae. Moth antennae, on the other hand, are usually slender or feathery and taper to a point.

2. Dolphins vs. Porpoises

You might have heard people use these words interchangeably, but dolphins and porpoises are very different. First off, there are way more dolphins than porpoises. The ocean dolphin family Delphinidae contains approximately 37 species, including bottlenose dolphins (like Flipper) and killer whales (like Shamu). But there are only about seven species in the porpoise family Phocoenidae. And there may soon be just six—one species, the panda-like vaquita, is nearly extinct.

In general, porpoises and dolphins have different body shapes. Porpoises tend to have rounded faces, chunky bodies, and triangular dorsal (back) fins. Many dolphins, on the other hand, have pointy faces, slender bodies, and curved dorsal fins. But there are exceptions—Risso’s dolphins, for example, have blunt heads.

Another distinguishing feature is tooth shape. Porpoise teeth are spade-shaped and dolphin teeth are cone-shaped. But that’s pretty hard to see unless you stick your head in their mouths.

3. Sheep vs. Goats

Domestic sheep and goats are both cloven-hoofed, four-legged creatures with soft muzzles and really strange eyes. Here’s an easy way to tell them apart: look at the tail. Goats usually hold their tails up, whereas sheep tails hang down.

They also have different eating habits. Sheep, like cows, are grazers—they move across a pasture like fluffy vacuum cleaners, scarfing down vegetation close to the ground. Goats, on the other hand, are browsers. They pick and choose their bites from plants that are a little higher up. They’ll even climb trees for choice morsels.

4. Lizards vs. Salamanders

Lizards and salamanders look a lot alike. They have long bodies and tails, and they generally crawl around on four legs. But looks can be deceiving. Lizards and salamanders are only distantly related; in fact, lizards are closer cousins to humans than they are to salamanders.

Lizards are reptiles, like snakes and turtles. Salamanders, on the other hand, are amphibians, like frogs. Look closely and you’ll see major differences: lizards have claws on their feet, but salamanders don’t (although there are one or two exceptions). Salamanders also lack scales; their skin is often smooth, moist, and slimy. Many species lack internal lungs, so their skin functions as an inside-out lung.

5. Hedgehogs vs. Porcupines

Let’s start with the basics: hedgehogs and porcupines are spiny. Those spines are made of special hardened hairs with hollow centers. But that’s about all these animals have in common. They aren’t closely related, and they evolved spines separately. And here’s the strange part: there are two groups of porcupine species—New World and Old World types—and they each evolved spines on their own. It’s just a useful evolutionary strategy!

Hedgehogs’ closest relatives resemble spineless hedgehogs; they’re mammals called gymnures and moonrats. Porcupines, however, belong to the order Rodentia—they are rodents. They may not look very rodent-y, but check out their big front teeth.

Porcupines use those chisel-like teeth to eat vegetation. Hedgehogs, on the other hand, have pointy teeth and snouts, and they’re omnivores, chowing down on frogs, insects, fruit, and more.

Hedgehog species inhabit parts of Europe, Africa, and Asia, but they’re not found in North and South America—so if you see a spiky animal in the New World, it’s a porcupine.

6. Crocodiles vs. Alligators

Alligators and crocodiles have a similar appearance, so it’s not surprising that they’re related: They belong to the order Crocodilia. One major difference is their salt tolerance. Crocodiles have special glands that help them excrete excess salt, so they’re comfortable in saltwater habitats such as coastal mangrove swamps. In alligators, those salt glands aren’t as well-developed, so gators are more likely to be found in freshwater.

Another difference is the shape of their heads. Crocodiles have longer V-shaped jaws, and alligator snouts are rounded and U-shaped. But there are exceptions; for example, the mugger crocodile of India and the surrounding region has a rounded snout like an alligator. Note that there are a couple of other members in the order Crocodilia that have extremely narrow snouts—the weird-looking false gharial and the even weirder-looking gharial.

Here’s another identification tip: take a look at the teeth. In crocodiles, the fourth tooth on the lower jaw sticks out, overlapping with the upper jaw and making the mouth look like a jigsaw puzzle gone horribly wrong.

7. Leopards vs. Jaguars

They’re both big cats, and they’re both speckled. But if you see a jaguar or leopard in the wild, it’s easy to figure out the species, because they live on separate continents. Leopards inhabit parts of Africa and Asia, and jaguars are found in South and Central America, as well as occasionally the southwestern United States.

Here are a few other ways to distinguish them. Both cats have clusters of dark spots on their fur, but jaguars have smaller spots inside each cluster. Leopards are also smaller and more slender than jaguars, and their tails are longer. You probably won’t need any of these tips, though, because these animals are notoriously secretive and hard to find.

A version of this story originally ran in 2016; it has been updated for 2023.

This article was originally published on www.mentalfloss.com as 7 Pairs of Commonly Confused Animals—And How to Tell the Difference.