尽管void和voidable是同根词，但是void contract和 voidable contract基本上没什么关系。如果非要说二者有什么关系，可撤销合同依法被撤销后和无效合同效力相同。

还是具体看一下什么是void contract和voidable contract。

A void contract is a formal agreement that is effectively illegitimate and unenforceable from the moment it is created. 

A contract may be deemed void if the agreement is not enforceable as it was originally written. In such instances, void contracts (also referred to as "void agreements"), involve agreements that are either illegal in nature or in violation of fairness or public policy.

参考译文：无效合同是一种正式的协议，但从它被创建的那一刻起，实际上就是非法的和不可执行的。

如果协议不能像最初写的那样执行，合同可能被认为是无效的。在这种情况下，无效合同(也称为“无效协议”)涉及非法性质或违反公平或公共政策的协议。

A voidable contract is a formal agreement between two parties that may be rendered unenforceable for any number of legal reasons, which may include:

Failure by one or both parties to disclose a material fact

A mistake, misrepresentation, or fraud

Undue influence or duress

One party's legal incapacity to enter a contract (e.g., a minor)

One or more terms that are unconscionable

A breach of contract

参考译文：可撤销合同是双方之间的正式协议，可能因多种法律原因而无法执行，这些原因可能包括:

·一方或双方未能披露重要事实

·错误、失实陈述或欺诈

·不正当的影响或胁迫

·一方在法律上没有能力签订合同(例如，未成年人)

·一个或多个不合理的条款

·违约

总而言之，二者关系不大，区别不小。无效合同从一开始就不具有法律效力(并且在未来的任何时间点都不具有强制执行效力)，一旦潜在的合同缺陷得到纠正，可撤销合同就具有法律效力。