I guess it could depend on how pedantic you are....
It can be argued that a "straight walled" case and a "straight case" can be different things. A straight walled case has straight walls because there is no shoulder. It can have no taper, a small amount of taper or a large amount of taper and still be a "straight wall" case.
A "straight" case is also a straight wall case, where the case walls are parallel from mouth to base.
General use terms generally describe the most obvious features and can be technically "sloppy" sometimes.
Particularly in English.....