Hi
@a_zed24! You may be comparing apples and oranges here. Furanose as you may know contain a 5-membered ring with 4 carbons and an oxygen. Of note, a furanose does not have any ketone groups. Furanose can be formed from an aldehyde (which
does contain a ketone group) through a reduction reaction. A ketose is a term used to describe a simple carbohydrate (monosaccharide) and contains a ketone group. Examples of ketoses include dihydroxyacetone, ribulose, and fructose and those differ by the number of carbons each molecule contains. Pentoses such as ribulose
can form a furanose but not all ketoses can form furanose.
Hope this helps!