Even if – Emphasises that something will/would happen or would have happened regardless of the condition. It means “incluso si…”
👉 You need to pretend you know what to do, even if you don’t.
Only if – Emphasises that a specific and strict condition must be fulfilled. It means “solo si…” The following expressions can be used as synonyms:
•As long as – 👉 I will like him as long as he keeps you happy.
•So long as – 👉 You can borrow the car so long as you don’t drive too fast.
•Provided (that) – 👉 We’ll go to the beach, provided that it stops raining.
•On condition (that) – 👉 You can go out on condition that you come home by seven.
Unless – Expresses a strict condition, It means “a no ser que…”. It replaces “If not”.
👉 We won’t get a table at the restaurant unless we get there early.
Otherwise – Used after an order or suggestion to show the result if you do not follow that order or suggestion.
👉 Start studying, otherwise you’ll fail the exam. (…, de otro modo/si no…)
In case (that) – To express that we are doing something in preparation for something which might happen. It means “por si acaso…”.
👉 We’ll cover the perimeter in case you need backup.