三者确实都可以指既判力，但也是有一定的差别的。

“Former adjudication”为英美法系中关于判决“既判效力”的原则，称为“先前裁决原则”或“既判效力原则”，指禁止当事人就已经作出判决的相同问题或主张重新进行诉讼（relitigation）。Former adjudication means adjudication in a former action. Former action can be a final determination of the right of the parties or a determination of a question of law. A former adjudication bars relitigation.

“collateral estoppel” 和“res judicata”分别是“Former adjudication”的两个方面（Estoppel by judgment and res judicata are the two branches of former adjudication.）：

“collateral estoppel”为“一事不二诉原则”，也称为estoppel by judgment; issue preclusion. 一旦法庭已经某一事项作出判决，则该决定将禁止案件当事方再就同一问题提出诉讼。（Collateral estoppel (CE), known in modern terminology as issue preclusion, is a common law estoppel doctrine that prevents a person from relitigating an issue. One summary is that, "once a court has decided an issue of fact or law necessary to its judgment, that decision ... preclude[s] relitigation of the issue in a suit on a different cause of action involving a party to the first case"）

“res judicata”为“一主张不二提原则”，也称为“res adjudicata、claim preclusion”。Generally, res judicata is the principle that a cause of action may not be relitigated once it has been judged on the merits. "Finality" is the term which refers to when a court renders a final judgment on the merits.

“collateral estoppel” 和“res judicata”两者的区别在于前者禁止当事人就某项已经裁决的具体事项再提起诉讼；而后者则是指禁止再提出某一诉讼主张或诉因。

以下为相关双语示例：

When the agency tried to relitigate the identical issue against Stauffer in another court, the Supreme Court held that the agency was precluded by collateral estoppel.

当该机关试图就同样的问题在另一个法院对斯道弗再次提起诉讼时，最高法院裁定，一事不二诉原则阻止其再次提出指控。

Even though the regional human rights courts may in a broader sense be considered monitoring bodies, they are included in the second category because their decisions constitute res judicata.

尽管区域人权法院可能在更广泛的意义上被视为监督机构，却被列入第二类，因为这些机构的决定构成既判力。