If you're in the market for a new moisturizer and looking at the long aisle of products in Sephora or a drugstore, it can easily be overwhelming. You'll likely see the words "moisturizing" and "hydrating" interspersed throughout different labels and brands and probably assume they mean the same thing. Well, not exactly.

Here, dermatologists explain the difference between the two, how to decide which you need (and specifically what ingredients to look for), and how to work both types of products into your skin-care routine for hydrated, healthy skin.

What Is the Difference Between "Moisturizing" and "Hydrating"?

Here's the deal: If you're seeing the words "moisturizing" or "hydrating" on any of your skin-care products, they both share the same goal—to help the skin get enough water to prevent or heal dry, tight, or dehydrated skin. Brands use the words interchangeably, which is what leads to a lot of confusion around deciphering between the two.

But the big difference between "moisturizing" and "hydrating" products, technically speaking, is how they work. "Hydrating products hydrate your skin cells, i.e. increase their water content," .

Moisturizing products, on the other hand, help to prevent trans-epidermal water loss — aka moisture that evaporates from your skin — reinforcing your skin's barrier function, says Dr. Feely. A well-functioning skin barrier is important for keeping bacteria and chemicals from entering the body and keeping the good stuff (including moisture) from leaving the skin.

 Hydrating products are all about increasing the water content in your skin cells themselves and moisturizing products are all about locking in that moisture.

Is Your Skin Dehydrated or Dry?

Now that you know the difference between moisturizing and hydrating skin-care products, how do you determine which you need? It all comes down to whether your skin is dehydrated or dry — and yes, those are two different things.

"Dehydrated skin describes the state of your skin: it lacks water, and this can manifest as tight, dry, rough, or peeling skin, and sometimes with sensitivity and redness if the dehydration is severe," says David Lortscher, M.D., board-certified dermatologist and CEO of Curology. Dehydrated skin is caused by external factors like — you guessed it — not drinking enough water, your diet, caffeine consumption, and the climate.

This is different than dry skin, which is something you don't have much control over. "Dry skin describes your skin type: it produces very little oil (sebum). It's possible to not produce much oil, yet have normal levels of hydration or moisture (i.e., water) in the skin," says Dr. Lortscher. "In this case, your skin would be dry, but not dehydrated."

To find the best one for your skin needs, you need to figure out the root of your skin's issues. Dehydrated skin needs a hydrating product, while dry skin needs oil and a moisturizing product. In other words, the difference between "moisturizing" and "hydrating" products really comes down to the ingredients inside the bottle.

Moisturizing Ingredients

Ceramides, dimethicone (a silicone-based smoothing agent), shea butter, and coconut oil, are just a few ingredients found in "moisturizing" skin products.

"Ceramides are naturally occurring lipids (fats) in the skin that help decrease dry skin and irritation, while silicones can act as lubricants, reducing friction and softening the skin," says Dr. Lortscher. Occlusives (like petroleum jelly, lanolin, cocoa butter, castor oil, mineral oil, and jojoba oil) all help to provide a barrier on the surface of the skin, helping to seal in hydration.

Hydrating Ingredients

As for hydrating products, look for ingredients that deliver water to the cells directly, like hyaluronic acid, propylene glycol, alpha hydroxy acids, urea, glycerin (also labeled as glycerol), and aloe, says Dr. Feely. All of these ingredients are humectants, meaning they work like magnets, pulling moisture from the deep layers of the skin (as well as from the environment) and binding them in the outermost layer of the skin, says Dr. Lortscher.

You probably recognize hyaluronic acid from that list — it's one of the buzziest ingredients around for good reason. "Using hyaluronic acid has shown a positive effect on the appearance of wrinkles and skin elasticity due to its moisture-binding properties, which help keep your skin plump and dewy," Dr. Lortscher says.

Another ingredient that may help, according to derms: Alpha hydroxy acids. Derived from sugar cane and other plant sources, the most common types of AHAs are glycolic acid, lactic acid, and citric acid. While you may think of them as exfoliators that help fight acne and signs of aging, they also hydrate by locking water into the skin.

How to Hydrate and Moisturize Your Skin at the Same Time

So what if your skin is both dehydrated and dry? Well, you can use moisturizing and hydrating products together to fight both skin issues. But the order you apply them matters.

Be sure to apply lighter-weight hydrating products first — for instance, a serum — to deliver water to your cells, followed by a heavier moisturizing product afterward to lock it in. (Otherwise, the moisturizing ingredient will prevent the hydrating ones from getting where they need to go.)

While your skin type likely will help you decide which is best for your skin, if you're unsure the best type for you, consult your dermatologist who can give you the best recommendation.