Botanically, bananas meet the definition of a berry while strawberries do not. The difference comes from how their flowers and ovaries develop into fruit
Botanical definition of a berry
A berry is a fleshy fruit that develops from the single ovary of one flower and contains seeds embedded in the flesh rather than on the surface.
Why bananas are berries
Bananas form from a single flower ovary and enclose tiny seeds within the flesh. Cultivated varieties have reduced seeds but retain the same developmental pattern that classifies them as berries botanically.
Why strawberries are not berries
Strawberries develop from a single flower with many separate ovaries, each ovary producing one of the small hardened fruits called achenes on the surface, so the strawberry as a whole is an aggregate fruit rather than a true berry.
Surprising botanical examples
Other common fruits that are true berries include grapes and tomatoes, while fruits often called berries in everyday language—raspberries, blackberries and strawberries—are not true botanical berries due to their multiple-ovary origin.
Takeaway
Common culinary names reflect taste and use, not botanical development. Understanding flower and ovary structure explains why bananas qualify as berries and strawberries do not.