hey,

bsc in aviation system is deals with design, maintenance of small size aircraft, management system in aviation lines,  production and operation in airlines etc.

while bba in management system deals with travel and tourism, management system in airlines, enterprise management , relationship building in airlines etc.

so this two are really different line and job fields is also different. both has job demand right now as many private airlines companies are setting business in india right now. so make decision as per your choice.