I'm not sure I really understand what your question is, but 'Ice Cream' is not a sport of 'Orinoco', they are very different plants. Vegetatively they can look similar, but when they flower they are easy to tell apart. Both have red/purple markings on the young fruit, but they are absent upon maturity. They also are not very waxy when young, but gain it as they mature.
As far "Cavendish vs. Gran Nain", that is not a logical comparison because 'Gran Nain' is a Cavendish cultivar, Cavendish being a subgroup of bananas which contains many different cultivars, 'Gran Nain' being just one.
Here are some photos of each, they are not very high quality because I don't have a very fast connection where I am, but you can see some differences, especially in the fruit.
Are you trying to ID the plant you have? If so you should add some photos here so we can see what you are questioning.
'Blue Java'/'Ice Cream'
'Largo'/'Orinoco'
