In HTML <strong> and <b> both exist and have a different meaning.

The <b> tag is for "offset text conventionally styled in bold". If you read deeper into the details you'll see it adds, "without conveying any extra emphasis or importance".

<strong> is different. It "represents a span of text with strong importance. " There is semantic meaning of importance here. In fact, a <strong> tag within another <strong> tag has even more importance there is nested importance.