Can someone please explain...?

Question

briefly the difference between claim and issue preclusion in civil procedure?

Answer 1

Claim preclusion prevents a party from attempting to re-litigate a claim (complaint) that has already been ruled upon.

Issue preclusion prohibits arguing one specific legal question, such as one element of a tort, even in unrelated proceedings.

For example, I sue you for assault, because you threw a bottle at me. The trial determines that you didn't throw the bottle. I then sue you for trespass, because the bottle landed on my property. That's not barred by claim preclusion because it's a different tort -- assault vs. trespass. However, issue preclusion can be raised as a defense, since the issue of whether you threw the bottle has been litigated. So, I'd have to prove my case, given the fact that you didn't throw the bottle.

Not a great example, but it's what came to mind.