It’s not unusual for social sciences, including economics, degrees to be styled as “of Arts” (the original form for both Bachelor’s and Master’s degrees); newer forms like (“of Science”), except for specifically professional degrees, are affectations which may or may not denote any substantive difference (some universities have different colleges with different core requirements independent of degree, that offer BS/MS vs BA/MA degrees, others simply offer only one style for any given major despite similar core requirements.)

Some universities might only offer one despite having a few programs in fields where it is more common for degrees to have the opposite style; at one time, e.g., this was true of Caltech which only issued BS degrees for undergrad though there were one or two majors with very few undergraduate degrees issued in fields where BA would be more common at other institutions.