Hi SteveS,
Welcome … and I’m glad you found us
There is more information in post #9 here about the different ways that one mattress can “match” or “approximate” another one. Every layer and component in a mattress (including the cover and any quilting materials) will affect the feel and performance of every other layer and component and the mattress “as a whole” so unless you are able to find another mattress that uses exactly the same type of materials, components, cover and quilting, layer thicknesses, layer firmnesses, and overall design (which would be very unlikely) then there really isn’t a reliable way to match one mattress to another one in terms of “comfort”, firmness, and PPP (Posture and alignment, Pressure relief, and your own Personal preferences) based on the specifications of the mattresses (even assuming that you can find out all the specifications you would need for both mattresses you are comparing in the first place).
If the only difference between two mattresses is 1/4" thickness in a single layer then it’s unlikely that you would feel much if any difference but you would need to know all the specs of every layer and component in both mattresses you are comparing to know whether a slight difference in a single layer is the only difference between them.
I’m not sure what you’ve read since you found the site but just in case you haven’t read it yet … the first place to start your research is the mattress shopping tutorial here which includes all the basic information, steps, and guidelines that can help you make the best possible choice … and perhaps more importantly know how and why to avoid the worst ones.
Two of the most important links in the tutorial that I would especially make sure you’ve read are post #2 here which has more about the different ways to choose a suitable mattress (either locally or online) that is the best “match” for you in terms of “comfort”, firmness, and PPP that can help you assess and minimize the risks of making a choice that doesn’t turn out as well as you hoped for and post #13 here which has more about the most important parts of the “value” of a mattress purchase which can help you make more meaningful quality/value comparisons between mattresses in terms of suitability (how well he will sleep), durability (how long he will sleep well), and the overall value of a mattress compared to your other finalists based on all the parts of your personal value equation that are most important to you (including the price of course and the options you have available after a purchase if your choice doesn’t turn out as well as you hoped for).
While nobody can speak to how any specific mattress will “feel” for someone else or whether it will be a good “match” in terms of comfort, firmness, and PPP because this is too subjective and relative to different body types, sleeping positions, and individual preferences, sensitivities, and circumstances and you are the only one that can feel what you feel on a mattress … outside of PPP (which is the most important part of “value”), the next most important part of the value of a mattress purchase is durability which is all about how long you will sleep well on a mattress. This is the part of your research that you can’t see or “feel” and assessing the durability and useful life of a mattress depends on knowing the specifics of its construction and the type and quality of the materials inside it regardless of the name of the manufacturer on the label or how a mattress feels in a showroom or when it is relatively new so I would always make sure that you find out information listed here so you can compare the quality of the materials and components to the durability guidelines here to make sure there are no lower quality materials or weak links in a mattress that would be a cause for concern relative to the durability and useful life of a mattress before making any purchase.
Night Therapy is a Zinus brand which is a Chinese manufacturer that makes a wide range of brands including Enso, Vivon, Spirit Sleep, Night Therapy, Keetsa and many others (see post #2 here). They tend to use lower quality/density and less durable materials in their mattresses than I would normally consider. A forum search on Zinus (you can just click the link) will also bring up more information about them as well. They are all manufactured in China and shipped compressed to North America so I would also read post #6 here for more about Chinese imports and some of the additional uncertainty and risk that can be involved in purchasing them.
You can also see my comments about the Consumer Reports mattress ratings and recommendations in post #2 here and in this topic. While they may be a good source of information about more “objective” purchases … as you can see I would consider them to be an unreliable source of information or guidance about purchasing a mattress and their “ratings” are somewhat nonsensical and meaningless. My thoughts are also shared by most of the more knowledgeable people in the industry (see post #5 here for an example).
There are also some suggestions for purchasing a mattress for a guest bedroom in post #2 here that may be helpful as well.
Phoenix