What is the difference between Lessons finished and Lessons have finished and Lessons are finished ?Feel free to just provide example sentences.

The easy answer is that there's only really a subtle difference in the nuance.... So it's difficult to explain. "Lessons finished" you CAN say to mean "lessons have finished" or "lessons are finished", and people do informally, but it doesn't really feel right to me to say it any other time than when you're explaining to someone quickly that your obligations are wrapped up, for example. It's more something I'd say if I were going to say something like "lessons finished are a blessing", but that has a different usage. As for the difference between "lessons have" and "lessons are", it's... Kind of a subtle difference or nuance as to the period in time WHEN they finished. Saying "the lessons have finished" is kinda like saying either "at last, they're over" or "they were already done a while ago". "The lessons are finished" is kinda like just a really straightforward factual statement: "now the lessons are over so you can go home." or "the lessons are over, that's all there is" etc. I realize this is probably a pretty poor explanation, too little too late, but in any case I hope this helps :)