Compare and analyze the origins and structure of the greek polis, the roman republic, and the roman empire. (700 b. c. to 400 a. d.) use specific examples to make your points. you may choose to conduct additional outside research on the topic to answer the question thoroughly.

 Greek polis were very diverse. The 2 best known being Athens and Lacedaemonians. One was ostensibly a Democracy (oligarchy is better description) the second was kinda a Socialistic Monarchy (it emphasized equality)… Many Polis had Tyrants, were Monarchies, were Democracies, etc.. all within the time period you asked for. In addition the founding of Greek Polis is a subject of debate without any real record being preserved. 
For instance Sparta list their first kings as descendants of Hercules… Their history is shrouded in speculation and myths.

Now Rome is a little bit easier to answer, but even then it is a matter of myths and who you would like to believe.

Nonetheless. Rome was founded in 753 (mythical founding of Rome, date contested) by Romulus and Remus as a Monarchy. Since there were no people in Rome really at that time, Romulus (who killed Remus) based his Kingdom on a premise that citizenship has its guarantees. This created a semi-Constitutional monarchy where people were rather more involved in the Government then it was a norm…as far as we know (there are indication that a lot of people in that region such as Volscian shared elements of such Government). 
After the death of Romulus Rome retain their kings, BUT the Senate, which started out as an advising body to Romulus, ELECTED their king. Numa, the 2nd king of Rome was elected this way. If Plutarch is to be believed, Numa never wanted to be a king and was essentially was begged into becoming one. Numa was very religious person who was very much interested in people’s welfare. He strengthen the power of the Senate, and created essentially a kind of Oligarchy. The 5 other Kings of Rome, by and large, followed this, although the last one.. the good ol’ Superbus tried to create more absolute monarchy. This didn’t go over very well, so he got kicked out.

Now we go into forming of a Republic. When Superbus was kicked out the reins of power were taken over by the Patrictians, an nobility who were richest and most respected families in Rome.

This is very important aspect of Rome. The culture of Rome was based upon the Family, which is better described as a clan. The head of this family was the Father, who was in all but name , the king of his family. He had power over life and death within the confines of his family, and he had lots of protection under the law. 
This transitioned itself into the Government as well.

Now these families were in constant odds with the Plebs, who were the rest of citizens of Rome. It is important to note that while poor were Plebs, their political power was limited. Money in Rome was how you gain office.

Rome in a lot of ways was built upon these conflicts between Plebs and Patricians, upon the notion of State > individual, of Fathers being rulers of their Clans, and yes the rule of Law. The Military and Civilian matters were one and the same, and if you wanted to climb the ladder of power (Cursus honorum) you needed prestige, money and military service.

Therefore Roman Republic was built within seeds of its destruction's as the continual internal conflicts were always simmering, often boiling over into drastic actions. Such as Plebs leaving Rome in middle of the War (only to return when Senate promised share of power).

This ultimately lead to Roman Principate i.e. Empire. Which was created due to string of civil wars which started with death of Tiberius Gracchi in 168bc, and culminating with Octavian taking the power after assassination of Ceasar.

The problem with this is that we are talking about over 1,000 years of history. Really from around 1200 BC (estimated date for fall of Troy) and 476AD, i.e. fall of Western Roman Empire. Such a huge spawn of time is impossible to put into a quick few paragraphs, as many books can and have been written about it.

If you can narrow down your question, better answer can be given.

In general though, Romans tended to be more State oriented, and more homogeneous in their culture. While Greeks tended to be far more loose in both their organization of the city States but overall culture as well. When one reads about any famous person in Athens, take Themistocles, you read about their huge successes, and eventual banishment. Their culture was one of strife within political arena. Now this was certainly true of Rome, but in almost all cases Rome came first, despite the struggles.

I hope this helps friend ^^

the national congress's powers over the states were specific and definite: it had the sole power to negotiate treaties, declare war, and make peace. all powers not granted to congress were reserved for state governments. congress had no power to levy taxes, for example.