hi,

see the two course you have mentioned is totally different in terms of theory paper, practical works.

mechanical engineering - physics and mathematics oriented course. mainly deals with machine design , materials science to design, analyze, manufacture process, and maintain mechanical systems. mechanical engineer generally deals with operation of machinery, designing system, maintenance  of machinery.

Civil engineering: It needs good concept of mathematics, physics. it consists the study of structural engineering, materials science, design, construction etc.

so both of the course is different and have ample work opportunity and higher study options.

hope you understand.