What is the difference between "sustain" and "maintain"?
Answer from a Native speaker
Great question. These verbs have similar meanings. To "maintain" something means to "upkeep" or "take care" of something so that the quality or state of it stays a certain way or does not deteriorate. For example, we may use this word to refer to the physical care of something, like houses or cars. Ex: It is important to maintain your house and make sure it is in good condition. Ex: The teacher maintains order in the classroom. To "sustain" something means to use effort keep or hold something at a specific level, otherwise the state of things may fall quickly. It implies that if something is used up and is not replaced or replenished, things will deteriorate very quickly. We might use this verb in situations related to natural resources, for example (the environment) or financial matters. Ex: If we continue to abuse the environment in this way, the world will no longer be able to sustain life. Ex: This level of spending is not sustainable.