Yes, there is a difference between Planck time and the concept of an instant or zero time.
Planck time is the smallest unit of time that is meaningful within the framework of quantum physics. It is derived from the Planck constant (h) and the speed of light (c) and is approximately equal to 5.39 x 10^(-44) seconds. Planck time represents the scale at which quantum effects become significant, and our current understanding of physics breaks down.
On the other hand, the concept of an instant or zero time refers to the notion of an infinitesimally small time duration or a point in time with no duration at all. It implies an exact and instantaneous occurrence without any measurable time interval. However, in the physical world, it is challenging to define or observe such an instant as it would require an infinitely precise measurement and would likely go beyond the limits of our current understanding of time and the nature of reality.
In summary, Planck time represents the smallest meaningful unit of time according to quantum physics, while the concept of an instant or zero time refers to an idealized notion of a time duration with no measurable length.