Fructofuranose vs fructopyranose What's the difference between the two molecules? I can always read about β-D-fructofuranose in the chemistry books, but unfortunately, I've never found any info concerning β-D-fructopyranose. Is there a big difference between them (apart from their ring structure)?
And where can the furanose and the pyranose form be found in nature?
They are isomers. Both of them have the same molecular formula ($\ce{C6H12O6}$) but different structures.



Structure of β-D-fructopyranose



Structure of β-D-fructofuranose