1. The problem asks to identify features that all squares have but some rhombuses do not. 2. A square is a special type of rhombus where all sides are equal and all angles are right angles ($90^\circ$). 3. All squares have four right angles, but some rhombuses do not have right angles; their angles can be oblique. 4. Therefore, the key feature that all squares have but some rhombuses do not is that all interior angles are equal to $90^\circ$. 5. Additionally, all squares have equal diagonals that bisect each other at right angles, while in some rhombuses, diagonals are unequal but still bisect at right angles. 6. To summarize, the defining feature is that all squares have four right angles, which some rhombuses lack.