Answer:
A population can show two types of growth, exponential or logistic. Exponential growth occurs in case of unlimited resources like unlimited food or space. Organisms in the population do not have to compete with each other and the population can grow indefinitely. Such a growth model shows J shaped curve when population size is measured against time.
Logistic growth occurs in case of limited resources and competition. The population has carrying capacity i.e. maximum number of individuals it can hold before the population growth becomes stagnant. This model shows S shaped curve when population size is measured against time.
In real life logistic growth is shown by populations. Exponential growth is not possible since the resources get used up after some time.