A VARIED DIET
Food equivalence means replacing one foodstuff with another, so long as they have similar nutritional properties.
Equivalent foodstuffs can belong to the same food group but equivalences also exist between groups.
For example you can get 10 g of fibre from 100 g of porridge oats or from 170 g of peas. Equivalences allow you to eat a variety of food while continuing to take in the essential elements your body needs and alternating the taste of your meals.
The choice of food depends a lot on availability and financial means and is also heavily influenced by social, cultural and religious customs. We cannot overlook the fact that food consumed by one person will be unpleasant to another.
A BALANCED DIET
Equivalences allow us to deal with these issues and eat a balanced diet whatever food is available, whatever food restrictions exist and whatever our personal tastes. If you do not like certain kinds of fruit, you could choose between a handful of apricots or cherries or even quarter of a melon.
All of these provide a roughly equivalent amount of carbohydrates.
We either choose to, or sometimes have to, avoid certain foodstuffs. We may not wish to eat meat on principle or wish to avoid pork for religious reasons, or have to avoid peanuts due to an allergy for example.
If there is not an excessive number of restrictions, the variety of food we can access should allow us to eat a balanced diet and satiate hunger.