The word assure can be used to describe the solidity of a promise. Assure is also used to remove any doubts or negativity in someone’s mind. Word assurance is a noun, and the word assured is an adjective. You could say, “ I am self-assured, and this will go well for me.” It means “assured results.” Assure could also mean to help someone overcome their anxiety over something.
Ensure, on the other hand, is used if you want to make sure that something will or will not occur in any case. Ensure is more like a guarantee of something that will or will not happen. You could say, “We are ensured that she will never speak of the matter.” It implies or provides confirmation. Ensure is more finite as if something has already been done.
There are many words in the English language that have a similar spelling, as well as a similar sound, but they mean two different things. Assure and Ensure are examples of that. Assure is used in the context of putting a person at ease. For example, "I assure you that the test will not be hard because Ms. Landry is an easy teacher." Ensure is more solidified because it is something that the person can control. For example, "I ensure you that your order will ship out by this evening, as I called the warehouse to make it a priority."
The words assure and ensure are two verbs that look synonymous but are actually different in usage, and they cannot be used interchangeably. The word ‘assure’ is used basically for or with a human being or anything that has life, while ‘ensure’ is usually used with respect to objects that do not have life. The word ‘assure’ means ‘to make sure and secure.’ It has to do with giving someone some sort of confidence in the trustworthiness of something. It simply has to do with guaranteeing promise. On the other hand, ‘ensure’ similarly means to promise, to guarantee, to assure, to make certain, usually used in association with some future event. Nevertheless, ‘assure’ seems to be of stronger conviction or affirmation than ‘ensure.’ When used in sentences, a noun or pronoun is usually used to immediately precede the word ‘assure,’ which is scarcely so for the word ‘ensure.’
When you are trying to assure someone, you are trying to put someone’s mind at ease. For example, someone would like to know if a project would be done in time. If you know that there is a big possibility that this will happen, then you would assure the person by saying facts as to why you think that this is possible would do it.
Ensure means that you are doing your best to guarantee that the task will be done on time. You may present hard pieces of evidence as to why you think this is going to happen. These terms are also different from "insure" which has a completely different meaning.
Assure and ensure are two English words that are mostly used whenever you want to increase people's hope about the possibility that something will happen. They can also be used to make certain promises. As much as they have similar meanings in some aspects, substituting one for another in a sentence might not produce the exact meaning you intended. For instance, you can decide to say that: I can assure you that you are going to pass the test. From this example, you can't substitute 'assure' for 'ensure' and still get the same level of confidence.
You can easily rest on people's promises when they use the word 'assure' than when they use to ensure. When you are assuring someone about something, it means you already have the capacity to make such things come into reality, but when you are using the word 'ensuring,' it means you don't really have the assurance; you just depend on your ability to make sure that something happens.