Does the security clearance process involve comparing the SF 86 employment activity to the resume ?
It can… it depends on if the customer (agency) orders it. Some agencies do it more often than others. If it is ordered and there are discrepancies then you will have to answer for the reason they do not reflect the same information.
Applications for cleared jobs and especially for federal jobs usually require you to account for all your employment history over the past 7-10 years including internships, unpaid jobs and periods of unemployment.
When applying for cleared or fed jobs, a good rule of thumb is to compile a record for yourself, that accounts for every period of your adult life (employment, unemployment, residence, travel, references, foreign contacts, education, etc) and use that as your source material when filling out your SF86.
Yes! So make sure they reflect the same employers, locations, dates & titles. And if it is a Fed resumé the same superrvisors.