Renewal和Extension都可用作指合同或契约期限的延续。

Renewal，强调重新指定法律关系或用一新合同取代旧合同。即合同的“续签”或“重新签订”。如：His contract is coming up for renewal.他的合同快到续订期了。

Renewal：the re-creation of a legal relationship or the replacement of an old contract with a new contract,as opposed to the mere extension of a previous relationship of contract

Extension，强调指同一合同或契约延续一定规定期间的效力。即合同的“展期”或“延长的期限”。如：It is also required an extension to your visa. 你的签证也需要延期。

Extension：An extension is an extra period of time for which something lasts or is valid, usually as a result of official permission.

参考双语例句：

The increase resulted from contracts from new customers and the renewal of a few long-term contracts from existing customers.

合约储备上升主要来自新客户合约及现有客户重新续签之一些长期合约。

As regards the proposal in the motion that the Government formulate standard contract terms and require all service providers of regulated services to adopt them, so as to protect consumer rights and avoid possible disputes, the Liberal Party is of the view that so long as the standard contract covers the major and crucial terms, for example, the arrangements for contract termination and automatic contract renewal, and so long as service providers are allowed to retain some flexibility, support can be given to this proposal.

至于议案建议政府制订标准合约条款，规定所有被监管的服务供应商均要跟从，从而保障消费者的权益及避免有可能出现的争拗，自由党认为只要标准合约能涵盖主要关键条款，例如解约和自动续约的安排等，并同时让各服务供应商保留一定的弹性，应该可予以支持。

While the complainant requested an extension of a deadline for his response to the State party’s observations on the merits with a justification of the need to seek further evidence from his contacts in the Democratic Republic of the Congo, he did not submit any new documents that would help to substantiate his allegations.

虽然申诉人要求延长他对缔约国关于案情的意见作出回应的截止期限，以使他能够从他在刚果民主共和国的联系人那里获得更多证据，但他并未提交任何有助于证实他的说法的新文件。

Consistent with its obligation not to provide source or special fissionable material, or equipment or material especially designed or prepared for the processing, use or production of special fissionable material to any non-nuclear weapon State for peaceful purposes unless the source or special fissionable material is subject to IAEA safeguards, and with decision 2, paragraph 12, of the 1995 Non-Proliferation Treaty Review and Extension Conference, with the exception of India, Canada will only authorize nuclear cooperation involving proliferation significant items with those non-nuclear-weapon States that have made an internationally legally binding commitment not to acquire nuclear weapons or other nuclear explosive devices and that have accepted IAEA safeguards on the full scope of their nuclear activities.

加拿大遵守以下义务：不将源材料或特殊裂变材料，或特别为处理、使用或生产特殊裂变材料而设计或配备的设备或材料，提供给任何无核武器国家以用于和平目的，除非这种源材料或特殊裂变材料受原子能机构各项保障监督措施的约束；并遵守1995年条约审议和延期大会第2号决定第12段的规定(印度除外)，加拿大将只批准同符合以下条件的无核武器国家进行涉及可能会扩散的物品的核合作：已作出不获取核武器或其他核爆炸装置的具有国际法律约束力的承诺，已接受原子能机构对其所有核活动的保障监督措施。

来源：译问