These changes occur very fast in a short period of time
These changes take hours, months or years to occur
Some changes may occur even in a split of a second
Examples: Growth of a seedling into a plant, formation of curd from milk, formation of fossil fuels from dead plants and animals, growth of a child into an adult, etc.
Examples: Bursting of a cracker, lightning in the sky, blinking of eyes, switching on a bulb, burning of paper, shooting from a gun, etc.