How does pollen differ from plant to plant/?

Depending on the similarity of the plant species.

Same species usually have similar looking or have similar function of pollen

whereas different species of plant differ in method of spreading their seeds therefore their seeds differ in shape size weight etc ...

a hibiscus plant containing a flower has pollen that are small and grainy which enables it to stick to insects when they come for the juicy nectar. For a coconut tree it has seed which large in size hollow and light weight enabling it to float in water and reach another place to grow and increase their species once again