Instruction Set: a set of instructions—the “vocabulary”—that a process of certain architecture understands (x86, MIPS, etc.)
Types of Instruction Set: ARMv7, ARMv8 (64-bit), MIPS, x86 (32, 64-bit). The concept of the instruction set supports the stored-program concept (idea that instructions and data are both stored in main memory, with a memory heirarchy.)