Why can we digest starch, but not cellulose?

Both starch and cellulose are made of glucose, one of the main sources of energy for the human body. Yet... we can digest starch that we find in things like potatoes or flour, but we cannot digest cellulose, a compound that is found in virtually every plant... Why?!? If you would like to share feedback or have a suggestion for a topic, I can now be reached on twitter under @ChemistryinEve1 or you can leave a comment on my website https://chemistryineverydaylife574446112.wordpress.com/. Alternatively, you can send an email to chem.podcast@gmail.com. Sources Chemistry of glucose linkages · https://en.wikipedia.org/wiki/Glycosidic_bond · https://en.wikipedia.org/wiki/Anomer · https://en.wikipedia.org/wiki/Polysaccharide Glycogen & Starch metabolism · https://findanyanswer.com/can-glycogen-be-digested-by-humans · Biochemistryby J. M. Berg et al. 9th Ed. 2019 ISBN 978-1-319-11465-7; p. 679ff · https://en.wikipedia.org/wiki/Starch · https://en.wikipedia.org/wiki/Glycogen · https://en.wikipedia.org/wiki/Glycogenolysis Cellulose digestion · https://en.wikipedia.org/wiki/Ruminant#Digestive_system_of_ruminants · https://en.wikipedia.org/wiki/Rumen · https://en.wikipedia.org/wiki/Cellulose · https://en.wikipedia.org/wiki/Cellulase · https://en.wikipedia.org/wiki/Hindgut_fermentation