Cause and effect: terms denoting a genuine legal cause and its effect can, within valid conditions, provide two directions of transfer: purchase ↔ ownership.
Mere means and legal result: the original legal expression may be used for the dependent one, but not the reverse without independent justification: emancipation → divorce, not automatically divorce → emancipation.
The task is to identify the actual legal connection, original case, and dependent effect. Similarity in ordinary language alone cannot establish direction or legal validity.