What is the difference between opcode and the instruction address?

Question

They sound very similar? Are they the same thing?

Answer 1

Opcode is operation code. It's the combination of bits that tell a computer what function to perform. Instruction address is the location where the instruction (opcode) is located.

Answer 2

The instruction address is how you refer to a location.
The opcode is the content of the location.

Imagine that the memory is like a daily calendar on which you have numbered all the leaves. The instruction address is analogous to the leaf number. The opcode is analogous to the date printed on a leaf.