The Membership Renewals Report shows up to date numbers whereas the lapsed section on the Activity tab shows a snap shot of the memberships during that time frame. The differences between the two would be the members listed on the lapsed section as active. For example, if a membership expired 12/31/2015 and they renewed on 1 /15/2016 they would not be included in the Membership Renewal Report for December but would be listed in the lapsed section with a current status of active.