I'm just going to equate Ravenna with Rome because it was one of multiple Western Roman capitals in the Late Empire and the city of Rome retained its 'spiritual' significance in a way that Ravenna never could. "Western" Rome lasted from 753 BC to c. 476 AD. That's about a thousand years. Constantinople was the capital of the Eastern Roman/Byzantine Empire from 330 BC to 1453 AD. So still about a thousand years. But of course those numbers don't tell much of a story, so I'll elaborate.

Rome was founded as just a collection of villages around 753 BC, and when the West "fell" in AD 476 AD the city of Rome had little significance as a center of political and military power. Constantinople on the other hand was a very old, large and important city for a long time before it became the capital of the East and by the time it was taken by Mehmed II in 1453 AD, it was once again just a city with a proud history and had not been the centre of a great military power for hundreds of years. I would like to equate Rome and Constantinople with their respective empires here, but as you can see it can't really be said that these empires lasted thousands of years as anything other than a formality. You probably wouldn't call Rome an empire until it conquered Italy and began expanding overseas in the 3rd century BC, and by the late 5th century AD that had all fallen apart. Similarly, in my mind Constantinople lost most of its real power between 1071 (Manzikert) and 1203 (the Fourth Crusade wrecking the place). So really, Rome as an empire lasted about 800 years and Constantinople a similar period of time.

If you just want to know why the West fell and the East survived, there's lots of reasons, beyond my ability to summarise. Important factors include the superior economic resources of the East, its more stable political, economic and military situation, and their ability to deflect huge barbarian forces such as the Goths and Huns away from their own territory into the struggling West. It was just in the right place at the right time really: Rome was at the centre of countless enemies and opportunists who began preying on it while it was overtaken by great weaknesses and turbulence, eventually collapsing the whole structure. The East was spared much of this stress, but eventually found itself in a similar position when Islam and later the Turks came onto the scene right in their backyard. It was then the East's turn to fall to potential historical forces.

I have grossly simplified this issue. But essentially, I wouldn't say Constantinople "did" anything that really caused it to outlast Rome. It was just in the right place at the right time, with the right resources and with enemies and challenges they could handle. But my talk of vague "historical forces" glosses over the actual decisions of the people who ran the East and the West, which must have factored into the equation. Alas, it is beyond my knowledge to go into that. Perhaps a user more knowledgeable in the Byzantine Empire or Late Roman Empire can be of more use in that regard.

Sorry, when I said Constantinople and Revanna I meant the political units, not the cities. My bad.