Problem: Sentence1: Run a new program on the Mac.
Sentence2: They ran twenty blood tests on me and they still don't know what's wrong.
Q: Does the term run mean the same thing in both these sentences?

Answer: the same meaning

Problem: Sentence1: An idea is not a unit that can be moved from one brain to another.
Sentence2: He was a member of a special police unit.
Q: Does the term unit mean the same thing in both these sentences?

Answer: different meanings

Problem: Sentence1: After the scare about foot-and-mouth disease a lot of people started eating fish instead of meat.
Sentence2: They have a chef who specializes in fish.
Q: Does the term fish mean the same thing in both these sentences?

Answer: the same meaning

Problem: Sentence1: Some people put the stress on the first syllable of "controversy"; others put it on the second.
Sentence2: Go easy on him, he's been under a lot of stress lately.
Q: Does the term stress mean the same thing in both these sentences?

Answer:
different meanings