Serta and Sealy are two of the largest and most well-known mattress companies in the world. Deciding which brand to go with can be challenging, since they'll often use different model names to describe what is basically the exact same mattress, and the price can vary greatly from store to store. There are several characteristics you should examine when comparing mattresses, including if it uses springs or foam, size, thickness and overall price. Comparing Serta and Sealy mattresses to each other requires some research.
Examine similar mattress types. Both Serta and Sealy manufacture innerspring mattresses, which use coiled springs to provide mattress firmness. They also manufacture memory foam and latex mattresses. Compare an innerspring mattress to an innerspring mattress and memory foam to memory foam for the most reliable comparison, since comparing memory foam to latex won't give you an accurate comparison of the two companies.
Look at a Serta mattress that you like and then ask the mattress salesman for its Sealy equivalent. Mattress makers change the names of their mattresses per store to make price shopping more difficult, according to Seth Stevenson of Slate. The salesperson should be familiar with what equivalents exist in the store between brands so you can make a more accurate comparison.
Decide on what thickness you prefer between the corresponding Serta and Sealy brands. Thickness is largely a marketing tool, since thicker mattresses look more comfortable without actually having any additional benefit compared to a thinner variety. But you may have an aesthetic preference regarding how high or thick the mattress is.
See if the mattress has a box spring. If the Serta and Sealy models are direct equivalents, they likely will either both have a box spring or both not have one. A box spring adds to the price of the overall package, however, so decide if you want to invest in one. They are intended to reduce the compression of the mattress and, therefore, make it last longer.
Lay down on the Serta and Sealy equivalents and see if one feels more comfortable than the other. Comfort should be the most important feature to look for in a new mattress.
Look at the prices between the two brands. If the difference in comfort is negligible, go with the cheaper one. Depending on the specific store you're in, one brand may be drastically cheaper than the other, though Serta and Sealy are fairly similar price-wise overall. This will depend on the store you are in, so shop around for best results.