Compilers translate a text to (typically) a lower level, optimized, which is stored for later execution. The length of time the output is stored is arbitrary.

Compilers translate a text to (typically) a lower level, optimized, which is stored for later execution. The length of time the output is stored is arbitrary. Interpreters operate sequentially in time. They take the compiler output, combine it with parameters from the world outside the cpu, and sequentially produce results that affect the physical world in some way, even if it’s just writing a result to memory. The interpreter may use the compiled text many times. At some point, it’s interpreters all the way down, at first in object code, then microcode. The ALU itself is a sequential hardware interpreter.