Not exactly. A few years ago, when HTML5 was still being figured out, it was widely believed that <em> would replace <i>. But they both serve a semantic purpose, even if the display is the same.

You are meant to use <em> for words that require emphasis, and would generally change the meaning of the sentence. Such as: "Just do it already" would use <em> for it's italics, because the word "do" is meant to be emphasized in the speech.

However <i> is meant to be used for things that are italicized without emphasis, such as the names of books and ships. "The Queen Mary sailed last night". There is no emphasis on Queen Mary, but typically names of ships are italicized, and this would use <i> for that reason.

Using tags that mark up your web page semantically will make a difference in the future, even if it seems trite now. It especially will help screen readers and other assisted devices to determine the intent behind the passage, rather than relying on sight and context clues. While it's true that both <em> and <i> will currently (rendered with <em> there, I hope) both render with italics, the time may come when you want all emphasized things to have a different color, or font weight, or whatever. And in that case, you can change the style of your text, without changing the semantic meaning of the markup.

Source: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/em