They all start off green then change to red and orange as they mature. The more mature they are the sweeter they are. Green capsicums are picked ripe but still green and are more bitter and less sweet than the others. They have firmer skin than the coloured and therefore have more “crunch”.  Yellow capsicums have a fruity taste, yet are milder than their orange or red counterparts. Orange capsicums are similar to yellow in that they have a bit less flavour than red capsicums but are just as sweet.  Red capsicums are the sweetest of all the colours with one red capsicum containing almost the equivalent to almost 2 teaspoons of natural sugar. The reason being is that they have been left to ripen on the vine for the longest time and therefore the sugar content keeps developing.  Their sweetness makes them perfect for salads.