In music, the fermata is much more than a rest. In a rest, there is a definite value where music stops for definite number of beats. In a fermata, how much longer it is held is up to the discretion of the performer or conductor. How much time to hold before the music continues is not fixed.
When I go on vacation, I know the vacation ends in a week and work resumes after. How about when God puts me on hold for a ministry? Does the music stop? In a fermata, the note is sustained even when the next note is not to be played yet. There seems to be something going on in the music even while on hold.