Hi Marie! Blending keeps the natural fiber in your fruits/veggies. Juicing removes the fiber so nutrients and sugars(!) hit your system immediately. It takes a lot more fruits/veggies to make the same volume of juice compared to blending, which means that juicing is often much more expensive and much higher in sugar (without fiber to buffer your blood sugar). The essay that tlc tlc linked below has a lot of good info.

Here is an essay that answers your question: https://simplegreensmoothies.com/juicer-vs-blender/
And here are two collections of Grokker videos that you might enjoy:
https://grokker.com/mind/collection/beverages-smoothies-juices-nutmilks-kefir/657286c44b549441964439f1
https://grokker.com/cooking/collection/beverages-alcohol/606fe3d940ba6b32542795cb