Jim had one of the original iMacs and he heard a 'pop' and the display died. A Cinema display he had connected also went down. So he has to buy a new computer. He's wondering what the difference is between th i5 and i7 processor. Leo says about $300. They're very similar.
The i7 does multithreading, which is great for video editing. Multithreading allows each core to do two things at once. He can check out this site for more in depth comparisons - https://www.cpubenchmark.net/.
Should he get a fusion drive? Leo doesn't recommend them. He really won't get that much benefit from it. An SSD by itself with an external drive is far better performance wise. Put the OS and Apps on the SSD and keep the data on the hard drive. That's the most bang for his buck.