The results could have been different if the treatment period had been longer. vs The results will be different if the treatment period had been longer.

Some examples from the web:

• It might have been different if the Province of Burgenland had granted a commercial guarantee, as a private investor and not as state aid.
• How it would have been different if I'd been a better parent.
• Nothing. Only that our whole lives might have been different if only I had acted.
• I wonder if things would have been different if we'd done it a long time ago.
• Things would have been different if they weren't trying to put my head in a box.
• You asked me if things might have been different if I had come to you with an open heart.
• It would have been different if this statement had come from the Council, as colegislator with Parliament.
• It would have been different if... if I had been there to help.
• I regret to say that I wish things could have been different.
• I'm sorry. I wish things could have been different.
• The small countries have their dignity too, and perhaps the outcome of the vote in Denmark would have been different if we had behaved differently in connection with one quite specific issue in recent weeks and months.
• Do you think things would have been different if you'd had kids?
• Your advice would have been different if you knew she was the other girl?
• For a while, I... thought it could have been different.
• And maybe if you'd seen that a little more, things could have been different, but...
• How things could have been different!
• Do you ever think about how things could have been different?
• things could have been different, Tom.
• If the Council had followed his directions, the basic conditions would have been different now.
• If the regional aid had not existed, decisions on investment might have been different.

Some examples from the web:

• If you are asked to estimate the walking speed of a man in a video, for example, your answer will be different if you're told to think about cheetahs or turtles.
• If the entry in BPX Field 15.012 is greater or less than 8, the number of bytes required to contain a pixel will be different.
• If the confidence of entrepreneurs is boosted, the result will be beneficial for productive investment and employment.
• Guys, maybe things would be different if the public knew what we know, but that's not the case.
• The atmosphere will be different, the pressures will be different.
• The situation today is different from the post-war era of 1951, but the challenges may be similar, even if the practicalities will be different.
• You'll wake up tomorrow and everything will be different.
• That the next place will be different.
• It will be different at Euro 2000, as this will be a football party for everyone.
• As soon as you truly renounce God everything will be different.
• The color of the sea will be different in fall.
• But today I have decided will be different.
• The future we experience will be different from what he encountered.
• And Sarah, this will be different from the last time.
• People will be different after the Revolution.
• I will be different for you.
• Believe me, everything will be different now.
• Because one day things will be different for your children.
• What will be different about him?
• Maybe I can do something, but the meat will be different.