IPhone and Android Phones are two of the top phones in the market in the present time. While ["While" is accurate in linking simultaneous events (meaning "during"), but if that is not the case here, use "although," "whereas," "and," or "but"] both phones offer great [Writing suggestion: "great" is an overworked word, too frequently seen, and too vague. It has too many meanings: huge, superior, numerous, etc. Use a more specific adjective] features; The programs and running software make each of the phone unique to each individual person. It is really [Writing suggestion--"real" or "really" means "existing in actuality"--it adds little to the meaning (and using it to mean "big," "very," or "genuine" is slang); replace it with a more expressive word] more of a preference for each individual person. There are many great features on each phone.
The programing which [Use "that" for a restrictive phrase (or place a comma before "which")] each phones system runs under is very different. The OS internal system of stacks is called [The passive voice is a form of "be" (is) and a participle (called). Over-use of the passive voice can make paragraphs officious and tedious to read. Prefer the active voice. For example, passive voice = The paper was completed on time. Active voice = the student completed the paper on time. See Center for Writing Excellence > Tutorials & Guides > Grammar & Writing Guides > Active & passive voice] the Kernel. Android which [Use "that" for a restrictive phrase (or place a comma before "which")] was developed [Passive voice ] under Google software uses the Google used the Linux version 2.6 OS to build Android's kernel, this also includes Android's memory management programs. Now ["Now" is a difficult word. Because this is being read some time after you wrote it, "now" is ambiguous--do you mean at the time you were writing? When was that? If you mean "as of the present time" (Hawaii is now a state), you can leave out "now." If the time or date is important, fill it in. If the essay is in the past tense, instead of "now," use "then"] IPhone OS is a mobile operating system developed and marketed by Apple Inc. It is the default operating system of the IPhone. It is a UNIX like OS that is [Wordiness: see if you can remove "that" or "that is"] derived [Passive voice ] from Mac OS X [Do not use all capitals in academic writing--unless in trade name, an acronym, or the running head ] . It is hard to say who would have the overall [Wordiness: unless meaning denim work clothes, "overall" is general and vague and contributes little to the sentence] advantage in this case because both networks are strong in my [Avoid use of the first person (I, me, my) in academic writing unless writing about a personal experience. First person use may be allowed by the instructor. ] opinion [Wordiness: Remove "in my opinion," which is unnecessary. By writing this, you are showing your opinion.]