There is one main difference between a functional resume and a chronological resume: the first showcases your professional skills, the latter your professional work history. Both the functional and chronological resume summarize your technical abilities and break down your experience, qualifications and achievements, but they follow unique formats to do so.
Functional resume: Uses multiple skills sections to define and elaborate on your soft, hard and technical skills, adding detail to each of your past successes.
Chronological resume: Uses work history to highlight past jobs, and links skills, responsibilities and professional accomplishments to each of your formal roles.