This is from another response about a similar question—-
Call alert: acts like old fashioned pager: on receipt of PL/DPL and QC tones, causes audible or visual indication of having been paged. Set as "OR", will also receive dispatch traffic.
Selective Call: uses QC to unmute receiver. Set as AND, radio does not unmute on normal dispatch traffic, but unmutes on voice traffic after receipt of QC tones. Depending on programming, stays unmuted to dispatch traffic (a) until manually remuted by button press or (b) until an auto reset timer expires. This way radio serves as a "Night Dispatch" or "Emergency Call-back" function. Set as OR, radio receives normal dispatch traffic, but will also unmute on RF sent with QC but no PL; used for private comms between two units not repeated for others.