Grapefruit is a citrus fruit created by crossing a pummelo with an orange. They have become more popular than ever during the 1990s and 2000s thanks to fad-dieters' embrace of the Grapefruit Diet.
These pale yellow colored fruits are the original variety of grapefruit before they were "improved" to the ruby red variety. White grapefruit are typically more tart than the pink variety.
Pink or ruby red grapefruit were created in Texas in 1929, according to Truestar Health, and have become extremely popular over the years. They lack the seeds of white grapefruit and have a sweeter taste.
This smaller variety of fruit is created when a grapefruit is combined with a Tangelo. They are smaller and have a bright red-orange skin when they mature. Typically these are available during the winter.
The largest fruit of its kind, they measure up to 12 inches in diameter, are pear shaped and have a greenish-yellow skin. They require heat to sweeten and are therefore best grown in subtropical climates.
Sweeties are extremely similar to pummelos because they are the combination of a grapefruit and a pummelo. They are slightly sweeter than a pummelo but vary little in size or nutritional value.