Scree is a collection of broken rock fragments at the base of crags and mountain cliffs that has accumulated over time. Scree is composed of fine, crumbly and crushed eroded rock that easily slides underfoot.
Talus is different as it involves large chunks of rock.
Rocks that accumulate on the scree fields and even Talus fields will roll down until they find a stopping point or they hit the bottom. Such fields are unstable (Scree) and when you step onto the loose rock, it has a tendency to give way. With Talus fields, they can be just as difficult to navigate because the stones are irregularly shaped, sharp, and can move under the weight of your feet.