What should be the true comparison ? 1. apple vs apple 2. apple vs guava 3. apple vs apple extract juice 4 apple vs melon

I would say apple vs apple.

I would go with apple vs. apple, but definitely not apple vs. Apple.

"Apple to Apple" would be my answer.

You would have to have the same brand name with the same manufacturing specifications to do a true analysis or comparison of a product from2 or more vendors to evaluate for pricing and lead time.

Two similar products can be only evaluated through a comparison,  having the same maufacturing specification, quality, pricing and lead time, however are no longer falls under the "apple vs apple".

This is however needed at times to find a better priced product with equal quality and better lead times. 

yes, it must be apple vs apple

1. apple vs apple

First one is Direct comparison rest are indirect or induced commparion. So for me all are true but first one is more relavent and important for industry of apple.

The way you put the question suggests tha apple vs apple is our prey

Good Day Zafar......

The logical & standardized comparison should be apple vs apple....... though on the basis of specialized needs, likings & dislikings, demands & priorities, rest can also be compared.  

the true comarison is between two same things in order to justify the advatages and disadvantages between them.

So apple vs. apple is the correct answer.

I agree with the responses, a true comparison would be apple vs apple

Apple vs Apple is the best Answer I would prefer.