They are used interchangeably a lot but they have a slight difference in meaning. "is responsible for something" means that you look out for it and make sure that it is ok. "to be held accountable to someone for something". the "to someone" is left out a lot. Now accountable actually focuses on the fact that if it goes wrong you will be held to account for the problem to somebody. As such it implies a hierarchy of responsibility and consequences such as fines if there are problems. so typically as long as everything is going good you are responsible for it. as soon as it goes wrong you will be held to account for the problem.

In business these days I have heard the phrase, "You are not responsible for this, but you are accountable for it." So this implies, for example, that if your employees' absence rate exceeds the target, you will be punished for it, even though you have no direct control over it. This is symptomatic of a bad place to work...

Lets try that again. accountable: required or expected to justify actions or decisions. so "accountable for" means that is you are required to justify all actions/decisions that were taken in regard to something. Note you don't have to actually do anything. responsable: having an obligation to do something, or having control over or care for someone, as part of one's job or role. "responsable for" means that you have an obligation to do something or care for somebody.

They are synonyms in English. You can use them almost interchangeably - only in very advanced English (C2 level) would you start focusing on the subtle difference between the two. However, "to be responsible for" is more commonly used and "to be accountable for" is quite formal and not very often used in daily speech. to be responsible for = to be accountable for e.g. You will be responsible for cleaning the living room. = you will be accountable for cleaning the living room.

"responsible for" is used when someone doesn't want to take the responsibility for what will happen in the future. For example in this sentence: You are responsible for your things. The speaker of this sentence will no longer get in trouble if something happens to your things. In the future you are on your own if something happens to your things. It is not the speaker's fault . whereas accountable for is used more when you want to blame someone for wrong doings that happened. For example: The state of Michigan should be held accountable for the bad quality of water in Flint, Michigan. In this sentence, the speaker is expressing that state of Michigan did something bad and they should take the blame. To summarize: Responsible for is used when the speaker doesn't want to the take blame for something that will happen in the future. Accountable for is used when the speaker wants to blame someone else for wrong doing that happened in the past. Hope this helps.