It is a very interesting question. I don’t think there are many explanations of the difference of these words. So I will try to break it down for you. Firstly, let’s look at the context in which you would use both words. We are have some memorable days throughout our lives. It might be the first day in school, our graduation, our wedding, or holding your child for the first time. These memories are unforgetable, therefore we call them ‘ memorable’. They are easy to remember, because of their significance, their unigu and unusual nature. At the same time we also can recall some legendary events. The end of World War II, the fall of the Berlin Wall, Obama’s ( Trumps) victory ( from different reasons), they all will be taught in history classes for centuries. They are remarkable enough to be well known and famous. Oftentimes , they do not have to have historic or political connotations. My mum says the Queens concert was truly legendary. I can imagine that for people who were in the audience it was one of the most memorable days in their life. If you talk about the historic point of view - a legendary event is objective. It is legendary because of its fame, it’s very well known for everyone and its impact is undeniable. Memorable is more subjective. You talk about an event being memorable for you or group of people. It has not ( yet) risen to the level of being legendary. It might, one day. Perhabs JLo and Shakira’s performance at Super Bowl was a memorable one and in a few years we will look back and say: Awh my God it was a legendary performace,. Short note: we often exagerrate something if we like it and say: God, it was legendary or it was epic. For example if you saw an amazing match or concert etc. Its’s idiomatic though. I think i hear people using the word legendary more since ‘ i met your mother’ series where main character uses it a lot to describe something ‘ cool’ Hope it helps.

'Memorable' would mean that the writer and her readers can remember it. Of course, that's not true :)

Memorable is not strong enough for this paragraph. On a scale of 1 to 10 memorable is a 4 and legendary is a 9 or 10.

Heroic is not appropriate and significant is also not quite the right feel.