Hi rob2121,
There is a wide range of different firmness levels in both regular memory foam and gel memory foam so it would depend on the specifics of the memory foams you were comparing. There is more information about gel memory foams in general in post #2 here.
Gel memory foams as a group tends to be faster responding, less temperature sensitive, and more “supportive” than non gel memory foams but it also depends on the specifics of how it is made and the type and percentage of gel that is in the memory foam. The best way to know the specifics of any memory foam you are considering would be a more detailed conversation with an online retailer or manufacturer who will be the best source of guidance about how their specific memory foam may compare to other types of memory foam on the market.
Your own experience may also be different than others because so much of the “feel” and “firmness” of memory foam can be subjective so when you are considering an online purchase then the return or exchange policies may also be an important part of your purchase decision and your personal value equation just in case your own experience is different from others or what you hoped for.
Phoenix