I don;t think there is much difference between the two except that zero hours contract are defended as a means of providing flexible working where it suits the employee when the other side is where workers have no guarantee of working hours to suit the needs of the employer. On top of that there is an additional government narrative that it is the reusability of employees to have enough employers collectively meeting an individual's living needs, irrespective of the fact that employer's are not required to provide working hour that fit around employees other working commitment. How many CEOs are too lazy to work 24 hours/day based upon the availability of their workforce? How many, for example agricultural employers provide 24 hours/day means of fruit picking and free transport to/form their 'main' employment/homes?