<human>:  What are the biggest differences between a blackberry and a raspberry?
<bot>: The biggest differences between a blackberry and a raspberry are their sizes and shapes. Blackberries are larger and rounder, while raspberries are smaller and usually come in clusters. Blackberries also have a much darker color, while raspberries are usually a pinkish red. Blackberries have tougher skins, while raspberries are much softer. Blackberries are also much sweeter than raspberries, which are known for their tart flavor.