Main Difference

The main difference between Attendance and Attendence is that the Attendance is a presence of a person at a location for a scheduled event and Attendence is a misspelling of attendence.

Attendance

Attendance is the concept of people, individually or as a group, appearing at a location for a previously scheduled event. Measuring attendance is a significant concern for many organizations, which can use such information to gauge the effectiveness of their efforts and to plan for future efforts.

Wikipedia

Attendance (noun)
The state of attending; presence.
"Attendance at the meeting is required."
Attendance (noun)
The count or list of individuals present for an event.
"The class sat down so that the teacher could take attendance."
Attendance (noun)
The frequency with which one has been present for a regular activity or set of events.
"John's attendance for the conventions was not good."

Wiktionary

Attendance (noun)
the action or state of going regularly to or being present at a place or event
"my attendance at church was very patchy"
Attendance (noun)
the number of people present at a particular place or event
"she is being blamed for the museum's low attendances"

Oxford Dictionary

Attendance (noun)
Attention; regard; careful application.
Attendance (noun)
The act of attending; state of being in waiting; service; ministry; the fact of being present; presence.
Attendance (noun)
Waiting for; expectation.
Attendance (noun)
The persons attending; a retinue; attendants.

Webster Dictionary