Most processors use something called "von neumann architecture". This means that the program and data use the same physical memory space. However, in most modern implementations it means the program and data use the same address space. This is a problem.
Using the 6502 as an example, let's say we want to do a jump. The opcode will take up one byte in memory, and the 16-bit address to jump to will take another 2 bytes. That means we'll need to do 3 memory loads just to load the instruction, since the data bus is only 8 bits. This is VERY wasteful.
Harvard architecture does something very different. In most Harvard architecture CPUs the program memory is as long as the longest instruction word. This means the maximum number of reads for any given instruction is one, since the whole instruction is stored in one word of memory. Going back to the 6502 example, that means we used 2 fewer loads.
You might be thinking "But I want to be able to load a program into RAM to execute it!". This leads me to the next category: "Modified Harvard Architecture". This is exactly what it sounds like; the processors use a modified version of Harvard architecture. AVR, a well-known microcontroller core, modifies Harvard architecture by allowing the program to modify flash memory, which is where the program is stored. You could easily replace a segment of flash memory with RAM if you were worried about read-write cycle limitations. This way, you have a way to modify program memory (which is useful for loading a program), yet you also get significantly increased performance.
You're dodging the question. Harvard architecture is better, due to reduced load times, which leads to more instruction per second. You not answering shows that you want to disagree, but can't actually find anything to disagree with.
You acting like a sea urchin shows that you aren't worth interacting with
The distinction between "program" and "data" has been questioned.
As a trivial counterexample, a compiler is a program that works on data in the form of a program and converts it to a more readily-executable program.
I think you've been watching too much Terry Davis.
Hominem te memento
Terry Davis never mentioned anything about von-neumann architecture or Harvard architecture, so I'm going to ask you to elaborate. You're a prime example of a book person though. You try to act like a smartass with your clever remarks when somebody questions your thought process, instead of addressing the actual question that was asked. That shows your limited understanding of the topic.
My daughter worked for Elon. I only give the following information to give perspective to my view. Her credentials: Valedictorian at a 5 star high school of over 3000 students with a 4.6 GPA. Stanford grad with both a BS in biomechanical engineering and a masters in mechanical engineering. Heavily recruited by Tesla, turning them down twice, before finally accepting a position in the advanced engineering design lab.
My daughter was sitting with other members of the design lab in an all hands presentation, when Elon took the stage. She had never met Elon or heard him speak and was very excited. The longer he spoke, the more uncomfortable she got. She started looking at her workmates and saw they were looking at each other. These are smart folks, and the more Elon talked, the more they realized how little he actually knew, making obvious mistakes, along with false leaps of logic etc. They saw through the buzzwords and hyperbole, and understood that, while his degree may have been in physics, his genius wasn’t (or even engineering for that matter). She was so disappointed, she called me that night to tell me what had happened. She was well treated at Tesla, but left some months later after being offered a job in an even more exciting startup in S.F.
It's honestly hilarious how you responded with your smartass remarks almost immediately when I posted, but you can't produce a response after several hours when you're asked to produce a post that actually answers the question. Talk about me in chat. I honestly don't give half a shit what any of you think of me. I'll just sit here laughing my ass off at the irony