Is there a different fruit very similar to oranges? I recently purchased a fruit, which is very similar to an orange but slightly different in taste, size and color. The fruit I purchased is about 3 inches in diameter, and has a reddish orange peel and a rich sweet citrus taste. Its internal structure is exactly like that of an orange. Is there is any such variety of oranges? Or it is an entirely different fruit? One of my friend also told me that it wasn't an orange, but wasn't able to recall the fruit's name.

I went to market again but could not find it. I don't know its name. What it is called? I wasn't able to find it on fruits stores on the Internet. If anybody knows what it is then please let me know. Its rich taste is unforgettable. I would love to know what fruit it is. It's neither grapefruit nor blood oranges.
There are hundreds of varieties of citrus fruits, in a great variety of colors, sizes (and very occasionally, even different shapes).  There is really no fundamental difference between the various citrus fruits--they all cross breed and hybridize extremely readily.

It is possible if you post a photo that someone might recognize the cultivar, but other than that all that can really be said is that you have a citrus fruit.