The initial state of a Turing Machine tape is that beyond the finite-length input, all of the rest of the infinite tape is blank. https://en.wikipedia.org/wiki

The initial state of a Turing Machine tape is that beyond the finite-length input, all of the rest of the infinite tape is blank. https://en.wikipedia.org/wiki/Turing_machine#:~:text=Cells%20that%20have%20not%20been%20written%20before%20are%20assumed%20to%20be%20filled%20with%20the%20blank%20symbol https://en.wikipedia.org/wiki/Turing_machine#:~:text=Cells%2... Whereas the Rule 110 Cyclic Tags engine requires the infinite tape to contain infinite repetitions of structured patterns, even in order to simply run "while(true)". That's a key difference. I also agree with zamadatix's sibling comment.