Youth mattresses are usually a lighter version of their adult counterparts, which means not as many coils, lighter weight foams, etc. I would look elsewhere for an adult mattress.

Having sold Sealy for many years, the "youth" label was marketing. Parents typically want to spend less on kids beds, so many companies aim specifically for that lower-end market. Spend as much as you can afford on good support for your child. I'd avoid all the thin layers of foam plus coils used in mainstream products. You pay so much for a company's advertising, you tend to get less product for the money. Good base foam or coil support plus a couple of inches of good foam are know to outlast the products described above. An eco-friendly futon can last for years…it they're too firm, add a topper! Go as green as you can to avoid exposing your child to toxic foams and flame retardants.

The short answer is No. Youth mattresses have significantly less coils in the bed. There is usually also a difference of materials used on top of the springs. A great example of this is looking at the difference between Simmons Beautyrest (Adult Line) and Beautysleep (Youth Line). If you put the 2 side by side, let's use a queen size for example because they have nice round numbers. Keep in mind there are always some exceptions when stores get "special" models designed specifically for them.

When it comes to coils the Beautyrest line has 800 individual wrapped coils in its base models. The Beautysleep line has 700 in the same space. This means that the coils are spaced out more creating gaps between them where you don't get support.

In those same beds, the Beautyrest will usually always have Memory Foams and Gel on top of the coils. The Beautysleep beds will usually have basic convoluted foams which don't offer any additional support - just squishy softness.

Again this is not always the case but usually (99% of the time) these are the main differences (coil count, coil type, layered material).