There are different factors to consider, in regards to existing flooring types, when choosing the type of flooring material for your home.
Contemporary homes usually have a concrete (screeded) ground floor. There are also suspended timber floors upstairs, generally speaking. Manufacturers will usually specify if a floor board is structural and it will be in a range of 18mm to 20mm, and upwards. Boards of this type are used for spanning across floor battens and joists. They will also give structural strength to support any household items.
An overlay product is satisfactory to use if an existing floor is already in place. These types don’t need to be ‘structural’ per se. They are created in a thickness range of 12mm to 15mm. Board types like this are good for marrying to other nearby floor surfaces, when an even flush is needed.